Edsall elaborates:
She has ruled it out, but a prompt withdrawal from the contest for the Democratic nomination offers Sen. Hillary Clinton the prospect of major rewards. One of the most inviting is the near certainty that the Obama campaign would agree to pay back the $11.4 million she has loaned her own bid, along with an estimated $10 million to $15 million in unpaid campaign expenses. In addition, Democrats, both those who are loyal and those who are opposed to her campaign, say the odds of her winning a top leadership spot in the Senate would improve dramatically if she gracefully conceded now. The icing on the cake includes an improved political climate, giving Hillary and Bill Clinton the opportunity to heal the rift with the black political community.
Alas, we're not talking about someone rationally capable of making this sort of concession.