diff --git a/packages/google-auth/google/auth/_regional_access_boundary_utils.py b/packages/google-auth/google/auth/_regional_access_boundary_utils.py
index c97bf8f484df..6845f0e18e5f 100644
--- a/packages/google-auth/google/auth/_regional_access_boundary_utils.py
+++ b/packages/google-auth/google/auth/_regional_access_boundary_utils.py
@@ -491,11 +491,36 @@ def start_refresh(self, credentials, request, rab_manager):
                 # A refresh is already in progress.
                 return
 
+            # Safely unwrap functools.partial wrappers to isolate the genuine request callable.
+            actual_request = request
+            partial_args = ()
+            partial_kwargs = {}
+
+            if isinstance(request, functools.partial):
+                actual_request = request.func
+                partial_args = request.args
+                partial_kwargs = request.keywords
+
+            # Execute the clone protocol on the concrete underlying request adapter.
+            lookup_request = actual_request
+            if hasattr(actual_request, "clone"):
+                lookup_request = actual_request.clone()
+
+            # Re-apply initial partial call arguments to the detached request adapter.
+            if isinstance(request, functools.partial):
+                lookup_callable = functools.partial(
+                    lookup_request, *partial_args, **partial_kwargs
+                )
+            else:
+                lookup_callable = lookup_request
+
             async def _worker():
                 try:
                     # credentials._lookup_regional_access_boundary should be async in the async creds class
                     regional_access_boundary_info = (
-                        await credentials._lookup_regional_access_boundary(request)
+                        await credentials._lookup_regional_access_boundary(
+                            lookup_callable
+                        )
                     )
                 except Exception as e:
                     if _helpers.is_logging_enabled(_LOGGER):
@@ -505,6 +530,29 @@ async def _worker():
                             exc_info=True,
                         )
                     regional_access_boundary_info = None
+                finally:
+                    # Cleanly terminate the detached private socket pool.
+                    if lookup_request is not actual_request and hasattr(
+                        lookup_request, "close"
+                    ):
+                        if inspect.iscoroutinefunction(lookup_request.close):
+                            try:
+                                await lookup_request.close()
+                            except Exception as e:
+                                if _helpers.is_logging_enabled(_LOGGER):
+                                    _LOGGER.warning(
+                                        "Failed to close cloned async request adapter: %s",
+                                        e,
+                                    )
+                        else:
+                            try:
+                                lookup_request.close()
+                            except Exception as e:
+                                if _helpers.is_logging_enabled(_LOGGER):
+                                    _LOGGER.warning(
+                                        "Failed to close cloned request adapter: %s",
+                                        e,
+                                    )
 
                 rab_manager.process_regional_access_boundary_info(
                     regional_access_boundary_info
diff --git a/packages/google-auth/google/auth/aio/transport/__init__.py b/packages/google-auth/google/auth/aio/transport/__init__.py
index 166a3be50914..d25ede281c6d 100644
--- a/packages/google-auth/google/auth/aio/transport/__init__.py
+++ b/packages/google-auth/google/auth/aio/transport/__init__.py
@@ -142,3 +142,7 @@ async def close(self) -> None:
         Close the underlying session.
         """
         raise NotImplementedError("close must be implemented.")
+
+    def clone(self) -> "Request":
+        """Create an independent detached copy of this request callable."""
+        return self
diff --git a/packages/google-auth/google/auth/aio/transport/aiohttp.py b/packages/google-auth/google/auth/aio/transport/aiohttp.py
index 642d15927d0f..338c5e2f7a53 100644
--- a/packages/google-auth/google/auth/aio/transport/aiohttp.py
+++ b/packages/google-auth/google/auth/aio/transport/aiohttp.py
@@ -203,3 +203,28 @@ async def close(self) -> None:
         if not self._closed and self._session:
             await self._session.close()
         self._closed = True
+
+    def clone(self) -> "Request":
+        """Creates a detached copy of this request adapter.
+
+        Returns:
+            google.auth.aio.transport.aiohttp.Request: An independent request adapter
+            running a new aiohttp.ClientSession with identical environment proxy and
+            trace configurations.
+        """
+        new_session = None
+        if self._session:
+            trust_env = getattr(self._session, "_trust_env", True)
+            trace_configs = getattr(self._session, "_trace_configs", None)
+            new_session = aiohttp.ClientSession(
+                auto_decompress=False,
+                trust_env=trust_env,
+                trace_configs=list(trace_configs) if trace_configs else None,
+            )
+        else:
+            new_session = aiohttp.ClientSession(
+                auto_decompress=False,
+                trust_env=True,
+            )
+
+        return Request(session=new_session)
diff --git a/packages/google-auth/google/auth/transport/_aiohttp_requests.py b/packages/google-auth/google/auth/transport/_aiohttp_requests.py
index e8321965e0db..33107719ce35 100644
--- a/packages/google-auth/google/auth/transport/_aiohttp_requests.py
+++ b/packages/google-auth/google/auth/transport/_aiohttp_requests.py
@@ -203,6 +203,37 @@ async def __call__(
             new_exc = exceptions.TransportError(caught_exc)
             raise new_exc from caught_exc
 
+    def clone(self):
+        """Create an independent detached copy of this request adapter.
+
+        Returns:
+            google.auth.transport._aiohttp_requests.Request: An independent request adapter
+            running an isolated aiohttp.ClientSession with identical environment proxy and
+            observability configurations.
+        """
+        new_session = None
+        if self.session:
+            trust_env = getattr(self.session, "_trust_env", True)
+            trace_configs = getattr(self.session, "_trace_configs", None)
+            new_session = aiohttp.ClientSession(
+                auto_decompress=False,
+                trust_env=trust_env,
+                trace_configs=list(trace_configs) if trace_configs else None,
+            )
+        else:
+            new_session = aiohttp.ClientSession(
+                auto_decompress=False,
+                trust_env=True,
+            )
+
+        return Request(session=new_session)
+
+    async def close(self):
+        """Cleanly release the underlying aiohttp ClientSession resources."""
+        if not getattr(self, "_closed", False) and self.session:
+            await self.session.close()
+        self._closed = True
+
 
 class AuthorizedSession(aiohttp.ClientSession):
     """This is an async implementation of the Authorized Session class. We utilize an
diff --git a/packages/google-auth/tests/test__regional_access_boundary_utils.py b/packages/google-auth/tests/test__regional_access_boundary_utils.py
index c612b60b8ed2..aeaaf68d260f 100644
--- a/packages/google-auth/tests/test__regional_access_boundary_utils.py
+++ b/packages/google-auth/tests/test__regional_access_boundary_utils.py
@@ -678,6 +678,7 @@ async def test_async_refresh_manager_session_closed_ignored(self):
         )
 
         request = mock.Mock()
+        request.clone.return_value = request
         rab_manager = mock.Mock()
 
         manager = (
@@ -694,6 +695,91 @@ async def test_async_refresh_manager_session_closed_ignored(self):
         credentials._lookup_regional_access_boundary.assert_called_once_with(request)
         rab_manager.process_regional_access_boundary_info.assert_called_once_with(None)
 
+    @pytest.mark.asyncio
+    async def test_start_refresh_async_clones_request_and_unwraps_partial(self):
+        import functools
+
+        credentials = mock.AsyncMock()
+        credentials._lookup_regional_access_boundary.return_value = {
+            "encodedLocations": "0xA30"
+        }
+
+        mock_request = mock.Mock()
+        mock_cloned_request = mock.Mock()
+        mock_request.clone.return_value = mock_cloned_request
+        mock_cloned_request.close = mock.AsyncMock()
+
+        # Wrap in a functools.partial to simulate AuthorizedSession.request() timeouts
+        partial_request = functools.partial(mock_request, timeout=180)
+
+        rab_manager = mock.Mock()
+
+        manager = (
+            _regional_access_boundary_utils._AsyncRegionalAccessBoundaryRefreshManager()
+        )
+        manager.start_refresh(credentials, partial_request, rab_manager)
+
+        await manager._worker_task
+
+        # Verify that actual_request.clone() was called
+        mock_request.clone.assert_called_once()
+
+        # Verify that the lookup ran on a re-wrapped partial of the cloned request
+        called_arg = credentials._lookup_regional_access_boundary.call_args[0][0]
+        assert isinstance(called_arg, functools.partial)
+        assert called_arg.func is mock_cloned_request
+        assert called_arg.keywords == {"timeout": 180}
+
+        # Verify that the cloned request was closed cleanly in the finally block
+        mock_cloned_request.close.assert_called_once()
+        rab_manager.process_regional_access_boundary_info.assert_called_once_with(
+            {"encodedLocations": "0xA30"}
+        )
+
+    @pytest.mark.asyncio
+    async def test_start_refresh_async_mimics_ephemeral_session_closed_bug(self):
+        # Specifically mimics the real-world race condition where a fast foreground main call
+        # pulls the rug out from under the background worker when using an un-cloned session.
+        import asyncio
+
+        manager = (
+            _regional_access_boundary_utils._AsyncRegionalAccessBoundaryRefreshManager()
+        )
+
+        class EphemeralRequest:
+            def __init__(self):
+                self.closed = False
+
+            async def __call__(self, *args, **kwargs):
+                await asyncio.sleep(0.05)
+                if self.closed:
+                    raise RuntimeError("Session is closed")
+                return "success"
+
+        ephemeral_req = EphemeralRequest()
+
+        credentials = mock.AsyncMock()
+
+        async def mock_lookup(req):
+            return await req()
+
+        credentials._lookup_regional_access_boundary.side_effect = mock_lookup
+
+        rab_manager = mock.Mock()
+
+        # Start the background refresh worker
+        manager.start_refresh(credentials, ephemeral_req, rab_manager)
+
+        # Simulate fast foreground primary call (completes in 10ms and closes the session)
+        await asyncio.sleep(0.01)
+        ephemeral_req.closed = True
+
+        # Await the background worker task to settle
+        await manager._worker_task
+
+        # Verify that the background worker hit the "Session is closed" error and failed open cleanly
+        rab_manager.process_regional_access_boundary_info.assert_called_once_with(None)
+
 
 def test_get_service_account_rab_endpoint(monkeypatch):
     from google.auth.transport import _mtls_helper
diff --git a/packages/google-auth/tests/transport/aio/test_aiohttp.py b/packages/google-auth/tests/transport/aio/test_aiohttp.py
index 553f35775fac..f9845c78df94 100644
--- a/packages/google-auth/tests/transport/aio/test_aiohttp.py
+++ b/packages/google-auth/tests/transport/aio/test_aiohttp.py
@@ -169,3 +169,21 @@ async def test_request_call_raises_transport_error_for_closed_session(
 
             exc.match("session is closed.")
             aiohttp_request._closed = False
+
+    async def test_request_clone(self):
+        request = auth_aiohttp.Request()
+        cloned = request.clone()
+        assert cloned is not request
+        assert isinstance(cloned, auth_aiohttp.Request)
+        assert cloned._session is not request._session
+        await request.close()
+        await cloned.close()
+
+    async def test_request_close(self):
+        request = auth_aiohttp.Request()
+        assert not getattr(request, "_closed", False)
+        await request.close()
+        assert request._closed
+        # Second call should be idempotent
+        await request.close()
+        assert request._closed
diff --git a/packages/google-auth/tests_async/test__regional_access_boundary_utils.py b/packages/google-auth/tests_async/test__regional_access_boundary_utils.py
index 268ee37261c8..944c2ae408fb 100644
--- a/packages/google-auth/tests_async/test__regional_access_boundary_utils.py
+++ b/packages/google-auth/tests_async/test__regional_access_boundary_utils.py
@@ -28,6 +28,7 @@ async def test_async_refresh_manager_start_refresh():
     }
 
     request = mock.Mock()
+    request.clone.return_value = request
     rab_manager = mock.Mock()
 
     manager = (