February is the cruelest month
The caucus format has obviously been a huge headache for the Hillary Clinton campaign. The problem for her is that you can’t manufacture victories in caucus states out of thin air. You need a strong ground organization. Hillary just didn’t put such an organization together (they pretty clearly were planning, early on, to have the nomination wrapped up by Super Tuesday), and so Obama simply crushed her in all the February caucuses (and what were there, like, ten of them)? A huge miscalculation by team Clinton. I’m pretty sure they realized their peril after Super Tuesday, but by then it was too late to salvage any strong showing in the remaining February caucuses, because it takes time to build a ground organization.So, they realized their only plausible remaining path to the nomination was strong wins in the those post-February primaries where the demographics look favorable to her.
Unfortunately for Clinton, salvaging residual delegates in the remaining February contests (a tempting strategy, no doubt, when you desperately need every delegate you can win) would have required doing some fairly serious campaigning, and that raises expectations. It may be in the end we’ll look back and all conclude that it was the Potomac contests that finally killed her, but they almost certainly would have killed her had her campaign gone in with guns blazing — giving media the opportunity to portray Virginia as a winnable state Clinton really needed to capture.
Fortunately for her, she probably can do well in Wisconsin. But already you can see the validity of the situation I outline above, because, now that she’s putting a lot of emphasis on Wisconsin, not winning there will be a much bigger deal