Obama won big. Last week I pointed to an interesting article by Jay Cost which argued against the idea that Obama had already built unstoppable momentum, and showed that demographics could account for his recent run of successes, leaving Texas and Ohio as likely wins for Hillary. Jay's update on Wisconsin is worth reading. If it is right, the news is bad for Hillary.

Hillary Clinton suffered a stinging blow last night, losing Wisconsin by 15 points. What is worrisome for her is that Obama seems to have broken into several of her core voting groups. This is the first real evidence of momentum we have seen on the Democratic side.

After the Potomac Primary last week, some argued that Obama had already begun to build momentum because of his large victories in Maryland, Virginia, and the District of Columbia. I thought this talk was hasty. Given the large number of African American voters in each contest, and given that white voters in all three primaries were quite wealthy - Obama's sizeable victories did not come as a surprise. In particular, 39% of all Maryland Democrats and 39% of all Virginia Democrats claimed to make $100,000 or more per year. So, it is hard to argue that Obama's success among whites was due to him peeling off portions of the Clinton coalition. What seems more likely is that he won handily because his best voting blocs were in good supply that day.

The same cannot be said for Wisconsin. Just 20% of Wisconsin Democratic voters claimed to make $100,000 or more per year. So, there is strong evidence that, at least last night, Obama expanded his voting coalition. Consider the following chart, which uses the exit polls to review Obama's margin of victory with key groups in the non-southern states in comparison to his performance with those same groups in Wisconsin last night.



So, for instance, Obama won white males in the non-South by 8 points prior to the Potomac Primary. Last night, he won them by 26 points, yielding a net increase of 18 points.

March 4th could settle it.