Dubya?
:-)
Clinton was President up until January 20, 2001, so we knew we had a President (Constitutionally eligible, legitimate) even while the 2000 election results were being sorted out.
We are well past that period in the election process this time. George W. Bush has served out his two terms.
We need a LEGITIMATE occupant of the Oval Office.
I don’t know how the process will work out. I don’t know if the 2008 election results would be considered void, or if Biden would be appointed Acting President (once his Constitutional bona fides were examined), or if Bush/Cheney would be called back to extend their second term just a little while longer until things were resolved.