The vice president said he believes "the Constitution constrains me from claiming unilateral authority to determine which electoral votes should be counted and which should not."
Arizona is the first of what is expected to be at least three challenges by GOP lawmakers attempting to overturn the results of the presidential election.
The federal appeals judge was spurned when Democrats supported him as a Supreme Court justice. Now the incoming Biden administration wants him to lead what it calls reform at the Justice Department.
NPR's Noel King talks to Raphael Warnock about his election victory, which puts control of the U.S. Senate within the Democratic Party's reach. The other Senate runoff is too close to call.