If Obama looks about to lose, she will announce her retirement so that the Dems can choose her successor.
But timing could be an issue. If she makes this decision in the summer of 2012, this would be a major campaign issue. And politics could actually influence Obama to pick somebody more moderate, so as to avoid a huge Supreme Court confirmation battle right before the election.
Since there are 47 Republicans, and still a few more moderate Democrats in the Senate, some of whom are up for re-election in 2012, Obama might have a huge fight on his hands if he was trying to nominate someone who was very very liberal. Just saying that this could be a political headache if it happens in the summer of 2012.
But would it be too late to get a replacement thru a divided Senate?