Turkana at The Left Coaster has what I think is the most sober assessment of how possible outcomes tomorrow in Ohio and Texas will impact the state of the race. The short version is that Clinton has to win the popular vote in both states (which would presumably give her a delegate win in Ohio and risks a delegate loss in Texas if the popular vote is close), while Obama has to win the popular vote in Texas or Ohio.
A large part of the assessment of how the outcome of tomorrow’s primaries will have on the Democratic nomination will be how it impacts the media narrative. A Clinton popular vote win in Texas that fails to be accompanied by a delegate total win still has the chance of being spun as a justification of Clinton’s continued presence in the race, particularly if she also holds on to win Ohio. While small Clinton victories in Ohio and Texas (say by 5% of the popular vote) are almost certain to not significantly impact Obama’s delegate lead, they would also assure that Clinton has justification for staying in the race in the eyes of those crafting the narratives of this race. Winning both would show Clinton’s continued appeal and success in very large states.
I don’t buy that winning big states by small margins is any meaningful signifier for how Clinton would perform there in the general election – just as I don’t think Obama’s failure to win California or New York had any impact on his ability or likelihood to win there if he is the nominee. But I also don’t doubt that if she wins Ohio and Texas, the Clinton campaign will be pressing the “Obama can’t win big states” narrative very hard.