Riding a wave of momentum from his trio of victories on Tuesday Rick Santorum has opened up a wide lead in PPP's newest national poll. He's at 38% to 23% for Mitt Romney, 17% for Newt Gingrich, and 13% for Ron Paul.

Part of the reason for Santorum's surge is his own high level of popularity. 64% of voters see him favorably to only 22% with a negative one. But the other, and maybe more important, reason is that Republicans are significantly souring on both Romney and Gingrich.

Romney's favorability is barely above water at 44/43, representing a 23 point net decline from our December national poll when he was +24 (55/31). Gingrich has fallen even further. A 44% plurality of GOP voters now hold a negative opinion of him to only 42% with a positive one. That's a 34 point drop from 2 months ago when he was at +32 (60/28).

If Gingrich dropped out 58% of his supporters say they would move to Santorum, while 22% would go to Romney and 17% to Paul. Santorum gets to 50% in the Newt free field to 28% for Romney and 15% for Paul.