diff --git a/.coveragerc b/.coveragerc
index a523466..f15c7c6 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -2,7 +2,6 @@
 branch = True
 
 [report]
-fail_under = 100
 show_missing = True
 omit =
     google/cloud/artifactregistry/__init__.py
diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
index da616c9..0954585 100644
--- a/.github/.OwlBot.lock.yaml
+++ b/.github/.OwlBot.lock.yaml
@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:c66ba3c8d7bc8566f47df841f98cd0097b28fff0b1864c86f5817f4c8c3e8600
+  digest: sha256:df50e8d462f86d6bcb42f27ecad55bb12c404f1c65de9c6fe4c4d25120080bd6
diff --git a/.kokoro/samples/python3.9/common.cfg b/.kokoro/samples/python3.9/common.cfg
new file mode 100644
index 0000000..8f1bcd7
--- /dev/null
+++ b/.kokoro/samples/python3.9/common.cfg
@@ -0,0 +1,40 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Build logs will be here
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+  }
+}
+
+# Specify which tests to run
+env_vars: {
+    key: "RUN_TESTS_SESSION"
+    value: "py-3.9"
+}
+
+# Declare build specific Cloud project.
+env_vars: {
+    key: "BUILD_SPECIFIC_GCLOUD_PROJECT"
+    value: "python-docs-samples-tests-py39"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-artifact-registry/.kokoro/test-samples.sh"
+}
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+    key: "TRAMPOLINE_IMAGE"
+    value: "gcr.io/cloud-devrel-kokoro-resources/python-samples-testing-docker"
+}
+
+# Download secrets for samples
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
+
+# Download trampoline resources.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
+
+# Use the trampoline script to run in docker.
+build_file: "python-artifact-registry/.kokoro/trampoline.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.9/continuous.cfg b/.kokoro/samples/python3.9/continuous.cfg
new file mode 100644
index 0000000..a1c8d97
--- /dev/null
+++ b/.kokoro/samples/python3.9/continuous.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.9/periodic-head.cfg b/.kokoro/samples/python3.9/periodic-head.cfg
new file mode 100644
index 0000000..f9cfcd3
--- /dev/null
+++ b/.kokoro/samples/python3.9/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.9/periodic.cfg b/.kokoro/samples/python3.9/periodic.cfg
new file mode 100644
index 0000000..50fec96
--- /dev/null
+++ b/.kokoro/samples/python3.9/periodic.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "False"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.9/presubmit.cfg b/.kokoro/samples/python3.9/presubmit.cfg
new file mode 100644
index 0000000..a1c8d97
--- /dev/null
+++ b/.kokoro/samples/python3.9/presubmit.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 4f00c7c..62eb5a7 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -16,7 +16,7 @@
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.4.0
+    rev: v4.0.1
     hooks:
     -   id: trailing-whitespace
     -   id: end-of-file-fixer
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ec2b197..1dfe012 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## [0.3.0](https://www.github.com/googleapis/python-artifact-registry/compare/v0.2.2...v0.3.0) (2021-06-23)
+
+
+### Features
+
+* add always_use_jwt_access ([#46](https://www.github.com/googleapis/python-artifact-registry/issues/46)) ([247d779](https://www.github.com/googleapis/python-artifact-registry/commit/247d779c881e7fdfc7696adcb3256ca06b3980c3))
+
+
+### Documentation
+
+* omit mention of Python 2.7 in 'CONTRIBUTING.rst' ([#1127](https://www.github.com/googleapis/python-artifact-registry/issues/1127)) ([#41](https://www.github.com/googleapis/python-artifact-registry/issues/41)) ([7ae05ed](https://www.github.com/googleapis/python-artifact-registry/commit/7ae05eddef4fce0f3f09774e835381f901a6a031)), closes [#1126](https://www.github.com/googleapis/python-artifact-registry/issues/1126)
+
 ### [0.2.2](https://www.github.com/googleapis/python-artifact-registry/compare/v0.2.1...v0.2.2) (2021-06-16)
 
 
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 17c450d..89fc8e3 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -69,7 +69,6 @@ We use `nox <https://nox.readthedocs.io/en/latest/>`__ to instrument our tests.
 
 - To test your changes, run unit tests with ``nox``::
 
-    $ nox -s unit-2.7
     $ nox -s unit-3.8
     $ ...
 
@@ -144,7 +143,6 @@ Running System Tests
 
    # Run all system tests
    $ nox -s system-3.8
-   $ nox -s system-2.7
 
    # Run a single system test
    $ nox -s system-3.8 -- -k <name of test>
@@ -152,9 +150,8 @@ Running System Tests
 
   .. note::
 
-      System tests are only configured to run under Python 2.7 and
-      Python 3.8. For expediency, we do not run them in older versions
-      of Python 3.
+      System tests are only configured to run under Python 3.8.
+      For expediency, we do not run them in older versions of Python 3.
 
   This alone will not run the tests. You'll need to change some local
   auth settings and change some configuration in your project to
diff --git a/docs/conf.py b/docs/conf.py
index f12c971..302ff61 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -80,9 +80,9 @@
 master_doc = "index"
 
 # General information about the project.
-project = u"google-cloud-artifact-registry"
-copyright = u"2019, Google"
-author = u"Google APIs"
+project = "google-cloud-artifact-registry"
+copyright = "2019, Google"
+author = "Google APIs"
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
@@ -281,7 +281,7 @@
     (
         master_doc,
         "google-cloud-artifact-registry.tex",
-        u"google-cloud-artifact-registry Documentation",
+        "google-cloud-artifact-registry Documentation",
         author,
         "manual",
     )
@@ -316,7 +316,7 @@
     (
         master_doc,
         "google-cloud-artifact-registry",
-        u"google-cloud-artifact-registry Documentation",
+        "google-cloud-artifact-registry Documentation",
         [author],
         1,
     )
@@ -335,7 +335,7 @@
     (
         master_doc,
         "google-cloud-artifact-registry",
-        u"google-cloud-artifact-registry Documentation",
+        "google-cloud-artifact-registry Documentation",
         author,
         "google-cloud-artifact-registry",
         "google-cloud-artifact-registry Library",
diff --git a/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/base.py b/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/base.py
index 1053822..ecd7f1f 100644
--- a/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/base.py
+++ b/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/base.py
@@ -25,6 +25,7 @@
 from google.api_core import retry as retries  # type: ignore
 from google.api_core import operations_v1  # type: ignore
 from google.auth import credentials as ga_credentials  # type: ignore
+from google.oauth2 import service_account  # type: ignore
 
 from google.cloud.artifactregistry_v1beta2.types import file
 from google.cloud.artifactregistry_v1beta2.types import package
@@ -56,8 +57,6 @@
     except pkg_resources.DistributionNotFound:  # pragma: NO COVER
         _GOOGLE_AUTH_VERSION = None
 
-_API_CORE_VERSION = google.api_core.__version__
-
 
 class ArtifactRegistryTransport(abc.ABC):
     """Abstract transport class for ArtifactRegistry."""
@@ -78,6 +77,7 @@ def __init__(
         scopes: Optional[Sequence[str]] = None,
         quota_project_id: Optional[str] = None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
         **kwargs,
     ) -> None:
         """Instantiate the transport.
@@ -101,6 +101,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
         """
         # Save the hostname. Default to port 443 (HTTPS) if none is specified.
         if ":" not in host:
@@ -129,13 +131,20 @@ def __init__(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
 
+        # If the credentials is service account credentials, then always try to use self signed JWT.
+        if (
+            always_use_jwt_access
+            and isinstance(credentials, service_account.Credentials)
+            and hasattr(service_account.Credentials, "with_always_use_jwt_access")
+        ):
+            credentials = credentials.with_always_use_jwt_access(True)
+
         # Save the credentials.
         self._credentials = credentials
 
-    # TODO(busunkim): These two class methods are in the base transport
+    # TODO(busunkim): This method is in the base transport
     # to avoid duplicating code across the transport classes. These functions
-    # should be deleted once the minimum required versions of google-api-core
-    # and google-auth are increased.
+    # should be deleted once the minimum required versions of google-auth is increased.
 
     # TODO: Remove this function once google-auth >= 1.25.0 is required
     @classmethod
@@ -156,27 +165,6 @@ def _get_scopes_kwargs(
 
         return scopes_kwargs
 
-    # TODO: Remove this function once google-api-core >= 1.26.0 is required
-    @classmethod
-    def _get_self_signed_jwt_kwargs(
-        cls, host: str, scopes: Optional[Sequence[str]]
-    ) -> Dict[str, Union[Optional[Sequence[str]], str]]:
-        """Returns kwargs to pass to grpc_helpers.create_channel depending on the google-api-core version"""
-
-        self_signed_jwt_kwargs: Dict[str, Union[Optional[Sequence[str]], str]] = {}
-
-        if _API_CORE_VERSION and (
-            packaging.version.parse(_API_CORE_VERSION)
-            >= packaging.version.parse("1.26.0")
-        ):
-            self_signed_jwt_kwargs["default_scopes"] = cls.AUTH_SCOPES
-            self_signed_jwt_kwargs["scopes"] = scopes
-            self_signed_jwt_kwargs["default_host"] = cls.DEFAULT_HOST
-        else:
-            self_signed_jwt_kwargs["scopes"] = scopes or cls.AUTH_SCOPES
-
-        return self_signed_jwt_kwargs
-
     def _prep_wrapped_messages(self, client_info):
         # Precompute the wrapped methods.
         self._wrapped_methods = {
diff --git a/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc.py b/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc.py
index 2746e25..c8a99c0 100644
--- a/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc.py
+++ b/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc.py
@@ -173,6 +173,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
+            always_use_jwt_access=True,
         )
 
         if not self._grpc_channel:
@@ -228,14 +229,14 @@ def create_channel(
               and ``credentials_file`` are passed.
         """
 
-        self_signed_jwt_kwargs = cls._get_self_signed_jwt_kwargs(host, scopes)
-
         return grpc_helpers.create_channel(
             host,
             credentials=credentials,
             credentials_file=credentials_file,
             quota_project_id=quota_project_id,
-            **self_signed_jwt_kwargs,
+            default_scopes=cls.AUTH_SCOPES,
+            scopes=scopes,
+            default_host=cls.DEFAULT_HOST,
             **kwargs,
         )
 
diff --git a/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc_asyncio.py b/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc_asyncio.py
index 00687fa..10344dc 100644
--- a/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc_asyncio.py
+++ b/google/cloud/artifactregistry_v1beta2/services/artifact_registry/transports/grpc_asyncio.py
@@ -101,14 +101,14 @@ def create_channel(
             aio.Channel: A gRPC AsyncIO channel object.
         """
 
-        self_signed_jwt_kwargs = cls._get_self_signed_jwt_kwargs(host, scopes)
-
         return grpc_helpers_async.create_channel(
             host,
             credentials=credentials,
             credentials_file=credentials_file,
             quota_project_id=quota_project_id,
-            **self_signed_jwt_kwargs,
+            default_scopes=cls.AUTH_SCOPES,
+            scopes=scopes,
+            default_host=cls.DEFAULT_HOST,
             **kwargs,
         )
 
@@ -219,6 +219,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
+            always_use_jwt_access=True,
         )
 
         if not self._grpc_channel:
diff --git a/setup.py b/setup.py
index 93804da..00e81ab 100644
--- a/setup.py
+++ b/setup.py
@@ -20,12 +20,12 @@
 import setuptools  # type: ignore
 
 name = "google-cloud-artifact-registry"
-version = "0.2.2"
+version = "0.3.0"
 description = "Artifact Registry API client library"
 release_status = "Development Status :: 4 - Beta"
 url = "https://github.com/googleapis/python-artifact-registry"
 dependencies = [
-    "google-api-core[grpc] >= 1.22.2, < 2.0.0dev",
+    "google-api-core[grpc] >= 1.26.0, <2.0.0dev",
     "libcst >= 0.2.5",
     "proto-plus >= 1.4.0",
     "packaging >= 14.3",
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index 477e2dc..34cdc7c 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -19,7 +19,7 @@
 #
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have foo==1.14.0
-google-api-core==1.22.2
+google-api-core==1.26.0
 grpc-google-iam-v1==0.12.3
 libcst==0.2.5
 proto-plus==1.4.0
diff --git a/tests/unit/gapic/artifactregistry_v1beta2/test_artifact_registry.py b/tests/unit/gapic/artifactregistry_v1beta2/test_artifact_registry.py
index 6871344..11dbf34 100644
--- a/tests/unit/gapic/artifactregistry_v1beta2/test_artifact_registry.py
+++ b/tests/unit/gapic/artifactregistry_v1beta2/test_artifact_registry.py
@@ -42,9 +42,6 @@
 )
 from google.cloud.artifactregistry_v1beta2.services.artifact_registry import pagers
 from google.cloud.artifactregistry_v1beta2.services.artifact_registry import transports
-from google.cloud.artifactregistry_v1beta2.services.artifact_registry.transports.base import (
-    _API_CORE_VERSION,
-)
 from google.cloud.artifactregistry_v1beta2.services.artifact_registry.transports.base import (
     _GOOGLE_AUTH_VERSION,
 )
@@ -67,8 +64,9 @@
 import google.auth
 
 
-# TODO(busunkim): Once google-api-core >= 1.26.0 is required:
-# - Delete all the api-core and auth "less than" test cases
+# TODO(busunkim): Once google-auth >= 1.25.0 is required transitively
+# through google-api-core:
+# - Delete the auth "less than" test cases
 # - Delete these pytest markers (Make the "greater than or equal to" tests the default).
 requires_google_auth_lt_1_25_0 = pytest.mark.skipif(
     packaging.version.parse(_GOOGLE_AUTH_VERSION) >= packaging.version.parse("1.25.0"),
@@ -79,16 +77,6 @@
     reason="This test requires google-auth >= 1.25.0",
 )
 
-requires_api_core_lt_1_26_0 = pytest.mark.skipif(
-    packaging.version.parse(_API_CORE_VERSION) >= packaging.version.parse("1.26.0"),
-    reason="This test requires google-api-core < 1.26.0",
-)
-
-requires_api_core_gte_1_26_0 = pytest.mark.skipif(
-    packaging.version.parse(_API_CORE_VERSION) < packaging.version.parse("1.26.0"),
-    reason="This test requires google-api-core >= 1.26.0",
-)
-
 
 def client_cert_source_callback():
     return b"cert bytes", b"key bytes"
@@ -152,6 +140,18 @@ def test_artifact_registry_client_from_service_account_info(client_class):
         assert client.transport._host == "artifactregistry.googleapis.com:443"
 
 
+@pytest.mark.parametrize(
+    "client_class", [ArtifactRegistryClient, ArtifactRegistryAsyncClient,]
+)
+def test_artifact_registry_client_service_account_always_use_jwt(client_class):
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        client = client_class(credentials=creds)
+        use_jwt.assert_called_with(True)
+
+
 @pytest.mark.parametrize(
     "client_class", [ArtifactRegistryClient, ArtifactRegistryAsyncClient,]
 )
@@ -5623,7 +5623,6 @@ def test_artifact_registry_transport_auth_adc_old_google_auth(transport_class):
         (transports.ArtifactRegistryGrpcAsyncIOTransport, grpc_helpers_async),
     ],
 )
-@requires_api_core_gte_1_26_0
 def test_artifact_registry_transport_create_channel(transport_class, grpc_helpers):
     # If credentials and host are not provided, the transport class should use
     # ADC credentials.
@@ -5655,82 +5654,6 @@ def test_artifact_registry_transport_create_channel(transport_class, grpc_helper
         )
 
 
-@pytest.mark.parametrize(
-    "transport_class,grpc_helpers",
-    [
-        (transports.ArtifactRegistryGrpcTransport, grpc_helpers),
-        (transports.ArtifactRegistryGrpcAsyncIOTransport, grpc_helpers_async),
-    ],
-)
-@requires_api_core_lt_1_26_0
-def test_artifact_registry_transport_create_channel_old_api_core(
-    transport_class, grpc_helpers
-):
-    # If credentials and host are not provided, the transport class should use
-    # ADC credentials.
-    with mock.patch.object(
-        google.auth, "default", autospec=True
-    ) as adc, mock.patch.object(
-        grpc_helpers, "create_channel", autospec=True
-    ) as create_channel:
-        creds = ga_credentials.AnonymousCredentials()
-        adc.return_value = (creds, None)
-        transport_class(quota_project_id="octopus")
-
-        create_channel.assert_called_with(
-            "artifactregistry.googleapis.com:443",
-            credentials=creds,
-            credentials_file=None,
-            quota_project_id="octopus",
-            scopes=(
-                "https://www.googleapis.com/auth/cloud-platform",
-                "https://www.googleapis.com/auth/cloud-platform.read-only",
-            ),
-            ssl_credentials=None,
-            options=[
-                ("grpc.max_send_message_length", -1),
-                ("grpc.max_receive_message_length", -1),
-            ],
-        )
-
-
-@pytest.mark.parametrize(
-    "transport_class,grpc_helpers",
-    [
-        (transports.ArtifactRegistryGrpcTransport, grpc_helpers),
-        (transports.ArtifactRegistryGrpcAsyncIOTransport, grpc_helpers_async),
-    ],
-)
-@requires_api_core_lt_1_26_0
-def test_artifact_registry_transport_create_channel_user_scopes(
-    transport_class, grpc_helpers
-):
-    # If credentials and host are not provided, the transport class should use
-    # ADC credentials.
-    with mock.patch.object(
-        google.auth, "default", autospec=True
-    ) as adc, mock.patch.object(
-        grpc_helpers, "create_channel", autospec=True
-    ) as create_channel:
-        creds = ga_credentials.AnonymousCredentials()
-        adc.return_value = (creds, None)
-
-        transport_class(quota_project_id="octopus", scopes=["1", "2"])
-
-        create_channel.assert_called_with(
-            "artifactregistry.googleapis.com:443",
-            credentials=creds,
-            credentials_file=None,
-            quota_project_id="octopus",
-            scopes=["1", "2"],
-            ssl_credentials=None,
-            options=[
-                ("grpc.max_send_message_length", -1),
-                ("grpc.max_receive_message_length", -1),
-            ],
-        )
-
-
 @pytest.mark.parametrize(
     "transport_class",
     [