But there's one bit of good news from Siena College, which is one of two pollsters that's been surveying the state regularly. In February and March, Clinton led Sanders by 21 points. Now, she leads him by 10.

This is one set of polls from one pollster. (Another pollster, Quinnipiac University, shows basically no change since mid-March.) But that Siena has been polling since early February allows us to get a sense for how support for the two candidates has changed.

There are a few things that stick out. First, that Sanders has benefited as people have made up their minds. Some of the shift since March comes from Clinton losing support, but some also comes from fewer people being undecided. (The margins of error make it hard to put too fine a point on this.) Sanders has also seen a huge increase in support from younger voters, which is not a surprise, while Clinton's lead with other demographic groups has fallen. Black voters still strongly prefer Clinton, but only by a 2-to-1 margin in the most recent Siena survey. Among whites and among men, the two are now basically tied. Update: As the Huffington Post's Ariel Edwards-Levy notes, Siena also shifted from registered to likely voters.