Clinton’s generally underperforming Obama in the Northeast, including in Maine, Connecticut, New York, New Jersey and Vermont. She’s running slightly ahead of him in California, however, and perhaps more surprisingly — given that it was Obama’s home state — well ahead of him in Illinois. Although, note that Clinton was born in Chicago. Overall, weighted by each state’s 2012 turnout, she’s running about half a percentage point behind Obama in these states. So perhaps there’s something to the notion that Clinton’s underperformance in blue states can help explain some of the seeming differences between state and national polls.
But I wouldn’t take this too far. The relative lack of polling in these states means that the data is noisy. It doesn’t make a lot of sense that Clinton is outperforming Obama in Washington but underperforming him in Oregon, for instance, as polls suggest. In some cases, the polls don’t match the demographics of the states very well either. Our polls-only model “thinks” that Clinton should be ahead in New Mexico by about 14 points, for example, based on the patterns it’s seeing in other states, and not just by 9.