diff --git a/google/auth/exceptions.py b/google/auth/exceptions.py
index 57f181e..e9e7377 100644
--- a/google/auth/exceptions.py
+++ b/google/auth/exceptions.py
@@ -57,3 +57,7 @@
         super(ReauthFailError, self).__init__(
             "Reauthentication failed. {0}".format(message)
         )
+
+
+class ReauthSamlChallengeFailError(ReauthFailError):
+    """An exception for SAML reauth challenge failures."""
diff --git a/google/oauth2/_credentials_async.py b/google/oauth2/_credentials_async.py
index b4878c5..e7b9637 100644
--- a/google/oauth2/_credentials_async.py
+++ b/google/oauth2/_credentials_async.py
@@ -75,6 +75,7 @@
             self._client_secret,
             scopes=self._scopes,
             rapt_token=self._rapt_token,
+            enable_reauth_refresh=self._enable_reauth_refresh,
         )
 
         self.token = access_token
diff --git a/google/oauth2/_reauth_async.py b/google/oauth2/_reauth_async.py
index 510578b..f74f50b 100644
--- a/google/oauth2/_reauth_async.py
+++ b/google/oauth2/_reauth_async.py
@@ -248,6 +248,7 @@
     client_secret,
     scopes=None,
     rapt_token=None,
+    enable_reauth_refresh=False,
 ):
     """Implements the reauthentication flow.
 
@@ -265,6 +266,9 @@
             token has a wild card scope (e.g.
             'https://www.googleapis.com/auth/any-api').
         rapt_token (Optional(str)): The rapt token for reauth.
+        enable_reauth_refresh (Optional[bool]): Whether reauth refresh flow
+            should be used. The default value is False. This option is for
+            gcloud only, other users should use the default value.
 
     Returns:
         Tuple[str, Optional[str], Optional[datetime], Mapping[str, str], str]: The
@@ -299,6 +303,11 @@
             == reauth._REAUTH_NEEDED_ERROR_RAPT_REQUIRED
         )
     ):
+        if not enable_reauth_refresh:
+            raise exceptions.RefreshError(
+                "Reauthentication is needed. Please run `gcloud auth login --update-adc` to reauthenticate."
+            )
+
         rapt_token = await get_rapt_token(
             request, client_id, client_secret, refresh_token, token_uri, scopes=scopes
         )
diff --git a/google/oauth2/challenges.py b/google/oauth2/challenges.py
index 7756a80..0baff62 100644
--- a/google/oauth2/challenges.py
+++ b/google/oauth2/challenges.py
@@ -25,6 +25,9 @@
 
 
 REAUTH_ORIGIN = "https://accounts.google.com"
+SAML_CHALLENGE_MESSAGE = (
+    "Please run `gcloud auth login` to complete reauthentication with SAML."
+)
 
 
 def get_user_password(text):
@@ -148,7 +151,30 @@
         return None
 
 
+class SamlChallenge(ReauthChallenge):
+    """Challenge that asks the users to browse to their ID Providers.
+
+    Currently SAML challenge is not supported. When obtaining the challenge
+    input, exception will be raised to instruct the users to run
+    `gcloud auth login` for reauthentication.
+    """
+
+    @property
+    def name(self):
+        return "SAML"
+
+    @property
+    def is_locally_eligible(self):
+        return True
+
+    def obtain_challenge_input(self, metadata):
+        # Magic Arch has not fully supported returning a proper dedirect URL
+        # for programmatic SAML users today. So we error our here and request
+        # users to use gcloud to complete a login.
+        raise exceptions.ReauthSamlChallengeFailError(SAML_CHALLENGE_MESSAGE)
+
+
 AVAILABLE_CHALLENGES = {
     challenge.name: challenge
-    for challenge in [SecurityKeyChallenge(), PasswordChallenge()]
+    for challenge in [SecurityKeyChallenge(), PasswordChallenge(), SamlChallenge()]
 }
diff --git a/google/oauth2/credentials.py b/google/oauth2/credentials.py
index 98fd71b..e259f78 100644
--- a/google/oauth2/credentials.py
+++ b/google/oauth2/credentials.py
@@ -54,6 +54,9 @@
 
         credentials = credentials.with_quota_project('myproject-123)
 
+    Reauth is disabled by default. To enable reauth, set the
+    `enable_reauth_refresh` parameter to True in the constructor. Note that
+    reauth feature is intended for gcloud to use only.
     If reauth is enabled, `pyu2f` dependency has to be installed in order to use security
     key reauth feature. Dependency can be installed via `pip install pyu2f` or `pip install
     google-auth[reauth]`.
@@ -73,6 +76,7 @@
         expiry=None,
         rapt_token=None,
         refresh_handler=None,
+        enable_reauth_refresh=False,
     ):
         """
         Args:
@@ -109,6 +113,8 @@
                 refresh tokens are provided and tokens are obtained by calling
                 some external process on demand. It is particularly useful for
                 retrieving downscoped tokens from a token broker.
+            enable_reauth_refresh (Optional[bool]): Whether reauth refresh flow
+                should be used. This flag is for gcloud to use only.
         """
         super(Credentials, self).__init__()
         self.token = token
@@ -123,6 +129,7 @@
         self._quota_project_id = quota_project_id
         self._rapt_token = rapt_token
         self.refresh_handler = refresh_handler
+        self._enable_reauth_refresh = enable_reauth_refresh
 
     def __getstate__(self):
         """A __getstate__ method must exist for the __setstate__ to be called
@@ -151,6 +158,7 @@
         self._client_secret = d.get("_client_secret")
         self._quota_project_id = d.get("_quota_project_id")
         self._rapt_token = d.get("_rapt_token")
+        self._enable_reauth_refresh = d.get("_enable_reauth_refresh")
         # The refresh_handler setter should be used to repopulate this.
         self._refresh_handler = None
 
@@ -241,6 +249,7 @@
             default_scopes=self.default_scopes,
             quota_project_id=quota_project_id,
             rapt_token=self.rapt_token,
+            enable_reauth_refresh=self._enable_reauth_refresh,
         )
 
     @_helpers.copy_docstring(credentials.Credentials)
@@ -296,6 +305,7 @@
             self._client_secret,
             scopes=scopes,
             rapt_token=self._rapt_token,
+            enable_reauth_refresh=self._enable_reauth_refresh,
         )
 
         self.token = access_token
@@ -366,6 +376,7 @@
             client_secret=info.get("client_secret"),
             quota_project_id=info.get("quota_project_id"),  # may not exist
             expiry=expiry,
+            rapt_token=info.get("rapt_token"),  # may not exist
         )
 
     @classmethod
diff --git a/google/oauth2/reauth.py b/google/oauth2/reauth.py
index fc2629e..1e496d1 100644
--- a/google/oauth2/reauth.py
+++ b/google/oauth2/reauth.py
@@ -275,6 +275,7 @@
     client_secret,
     scopes=None,
     rapt_token=None,
+    enable_reauth_refresh=False,
 ):
     """Implements the reauthentication flow.
 
@@ -292,6 +293,9 @@
             token has a wild card scope (e.g.
             'https://www.googleapis.com/auth/any-api').
         rapt_token (Optional(str)): The rapt token for reauth.
+        enable_reauth_refresh (Optional[bool]): Whether reauth refresh flow
+            should be used. The default value is False. This option is for
+            gcloud only, other users should use the default value.
 
     Returns:
         Tuple[str, Optional[str], Optional[datetime], Mapping[str, str], str]: The
@@ -324,6 +328,11 @@
             or response_data.get("error_subtype") == _REAUTH_NEEDED_ERROR_RAPT_REQUIRED
         )
     ):
+        if not enable_reauth_refresh:
+            raise exceptions.RefreshError(
+                "Reauthentication is needed. Please run `gcloud auth login --update-adc` to reauthenticate."
+            )
+
         rapt_token = get_rapt_token(
             request, client_id, client_secret, refresh_token, token_uri, scopes=scopes
         )