One thought on last night's Democratic debate. It seems clear Hillary Clinton has decided to wrap herself in the mantle of President Obama, and in effect run for Obama's third term.

In a way, that makes sense: Obama remains very popular among Democrats. For example, in the most recent CBS/New York Times poll, where Obama's overall approval is 46 percent to 47 percent disapprove, his numbers among Democrats are 81 to 13. On the other hand, that same poll shows a plurality of Democrats (47 percent to 45 percent) think the country is on the wrong track (the overall number is 65-27).

If Clinton can make the Democratic primary a referendum on Obama, she'll win. If Sanders can make it a referendum on the state of the nation, he has a real shot.