Santorum: 37 (39)On the surface, those numbers are somewhat disturbing if you're rooting for a Rick Santorum win: his lead over Mitt Romney has shrunk from 15 points to just 4 in the span of a week. Based purely on the toplines, this is more a function of Romney's rise (up 9) than Santorum's fall (down 2), but part of what's going on here might be explained by the fact that in last week's survey, 48 percent of voters said they were evangelicals compared with 41 percent in this week's survey. Given that Santorum and Romney are evenly matched among non-evangelical voters, that's a very big shift, and probably explains much of what's going on in the trend line.
Romney: 33 (24)
Paul: 15 (12)
Gingrich: 10 (11)
By way of reference, 39 percent of the 2008 Republican primary electorate in Michigan was evangelical, which is more in line with newer numbers. And viewed in the context of other surveys, PPP's latest poll actually shows a slightly smaller Santorum lead. As of the writing of this post, for example, Nate Silver's survey-based forecast projects Santorum with a 5.5 percent win.
To be clear, I don't think any of this means that Santorum is a lock to win the Michigan primary. But I do think he's in the lead, and I don't think Romney's surging—at least not yet. And Wednesday's debate will probably play a big role in shaping how things ultimately play out.