Greg Sargent digs into the latest Pew poll:

In November, Romney was beating Obama among [independents], 53-41. Now those numbers are upside down: Obama is beating Romney among them, 51-42. That’s a net 19 point net swing of independents in Obama’s direction in three months.

Meanwhile, Rick Santorum is leading in Michigan.

The mounting danger for Romney is that his candidacy will lose its central justification: That he’s the most electable Republican in the field. Readers know I’ve long been bullish on Romney’s prospects, but if Santorum can pull out a win in Michigan, and Romney's numbers keep sliding, it becomes hard to see how he pulls this out.