Solus,
I believe that the members of the Electoral College vote for each the president and the vice-president so Biden could be declared the winner as having received more votes than, say, Romney. But, if SCOTUS declared the elections invalid, then the dilemma would present itself. I say again, they won't do that and it would be 5-4 or 6-3 against doing that with Roberts doing his Obamacare thing again.