All eyes are on Missouri Senate candidate Todd Akin, who is facing mounting calls to end his candidacy amidst the fallout from his controversial remarks on rape.

Rep. Akin faces a 5:00PM Tuesday deadline to withdraw from the race and allow someone else to take on Sen. Clare McCaskill, a vulnerable Democratic incumbent whom Republicans have made a key target. Here are the possible scenarios:

Akin withdraws today: If Akin bows to the pressure and takes one for the party, the Missouri Republican party committee then nominates a new candidate to fill his spot. It would have until Sept. 18 to fill the vacancy. The nominee would not be submitted to a popular vote.

Akin withdraws later: This is trickier, but it's not impossible. Akin would need to apply for a court order affirming his exit from the race. In this case, the final day to withdraw without a court order would be Sept. 25. 

Akin remains: And marks the launch of his general election campaign (he overcame two Republican rivals in a primary election less than two weeks ago) with a gaffe that has made national news and drawn the ire of his party. Initial polling shows that Akin is neck-and-neck with McCaskill despite widespread disapproval for his comment, so he could still have a shot.