It's Sunday night so I'm outsourcing to a friend who flags this from Politico:

Some supporters of Democratic Sen. Barack Obama suggested on the Sunday shows today that rival Sen. Hillary Clinton should reevaluate whether to stay in the race if she fails to win Tuesday’s contests in Texas and Ohio by large margins.

Says my correspondent: 

methinks obama's people are sensing she might win ohio and tx by small margins. if she wins both states by a combined two votes there's no chance she's getting out. i realize what they're saying, but if she takes 3 states--RI looks possible-- she's not getting out even if she splits delegates with obama. i'm not saying her chances of getting the nomination greatly improve, but her fundraising will spike and there's no reason after spending her whole life running for this moment she's not going to play out the hand thru PA.

--Michael Crowley