As Noam explains, the muddiest outcome tonight would be a Hillary victory in Ohio and an Obama victory in Texas. Would such an outcome force Hillary from the race? Noam thinks it would--at least after a few more days of campaigning. But something tells me that, should tonight produce a splitdecision, the Clinton people will be pointing to this as justification for her staying in:

Democrats by more than a 2-1 margin say Hillary Clinton should stay in the presidential race even if she loses either the Texas or Ohio primary on Tuesday. But if she fails in both, fewer than half say they'd want her to fight on.

I'd imagine, though, that the Clinton folks won't be calling much attention the poll's other big finding: that a pluarlity of Dems surveyed want Hillary to be Obama's veep.

--Jason Zengerle