National poll: Santorum 36, Romney 26, Gingrich 13, Paul 11

In a separate USA Today/Gallup survey conducted Feb. 16-19, all Americans were asked which of the two candidates — Romney or Santorum — they believed would have the best chance of beating Barack Obama in November. Overall, 54% of Americans named Romney and 29% chose Santorum.

Fewer Republicans are undecided on this issue, leaving 58% who say Romney has the best chance of beating Obama, while 32% choose Santorum.