Quinnipiac: Rick Santorum takes lead in Ohio

Quinnipiac. February 7-12. Republican primary voters and registered voters. ±2.6%. (No trendlines for primary.)

Santorum: 36
Romney: 29
Gingrich: 20
Paul: 9

You won't be shocked to learn that Romney's strongest group is those making over $100,000 per year: He takes 40 percent of upper income voters, compared with 28 percent for Santorum and 22 percent for Gingrich.

One of Santorum's strengths is that his supporters are more committed to voting for him than for Romney. More than half of his voters say they won't change their mind compared to two-fifths for Romney.

Santorum: 54
Romney: 39
Gingrich: 48

That means Santorum starts with about 19 percent of the vote while Romney starts with 15 percent. That's not a huge gap, but with the primary about three weeks away, it's a significant head start.

If Rick Santorum does win the primary, however, he might be not celebrating for long: President Obama leads him by six points. Obama leads Ron Paul by the same amount and edges out Mitt Romney by a smaller two point margin. He whoops Newt Gingrich by 12 points. (Trendlines are from January.)

Obama: 46 (44)
Romney: 44 (42)

Obama: 47 (48)
Santorum: 41 (37)

Obama: 46 (48)
Paul: 40 (39)

Obama: 50 (52)
Gingrich: 38 (38)

Probably the best piece of news in the poll from Mitt Romney's perspective is that while his net favorability is under water (37 favorable, 41 unfavorable), 61 percent of likely primary voters have a favorable view of him. Santorum is only one point higher, at 62. The big difference: Santorum's unfavorable rating is just 7, compared to 25 for Romney. Romney has time to raise that unfavorable rating, and given that his favorable number is on par with Santorum, he's got some room to maneuver in.

(This post was updated with general election trendlines.)