The latest Public Policy Polling survey shows Rick Santorum leading Mitt Romney by 15 percentage points in the Republican presidential race. In the wake of his upset victory in Colorado and his lopsided wins in Missouri and Minnesota, Santorum now has 38 percent support nationally among usual Republican primary voters, compared to 23 percent for Romney. Newt Gingrich has 17 percent support, and Ron Paul has 13 percent, which puts Paul closer to Romney than Romney is to Santorum.  

Santorum is dominating among Tea Party voters. He has 51 percent support among the Tea Party, compared to 12 percent for Romney. (Gingrich is in between, with 24 percent support, while Paul has 8 percent support.)