WASHINGTON (Reuters) - President Joe Biden said in an interview broadcast on Tuesday that he and his administration are trying to determine whether he has the authority to act on his own to shut down the U.S.'s southern border with Mexico to migrants, should it be deemed necessary.

       Biden told Univision in the interview that because bipartisan legislation that would have granted him the authority to shut the border was stalled by Republicans in Congress, he was being encouraged to try to do it alone.

       "We're examining whether or not I have that power," Biden said, adding there was "no guarantee" he has the power without legislation.

       Migration is a central issue in this year's presidential campaign. Former President Donald Trump, Biden's likely Republican opponent in the Nov. 5 election, has accused Biden of bungling border issues.

       (Reporting By Steve Holland; Editing by Heather Timmons and Eric Beech)