Romney leads Santorum, trails Obama

WASHINGTON, March 14 (UPI) -- Mitt Romney is back in the lead for the Republican presidential nomination, but falls behind President Obama in a general election matchup, a poll indicates.

In addition, Obama's approval rating has reached 50 percent for the first time since last May's killing of Osama bin Laden, a national survey by the Pew Research Center for the People & the Press indicated.

The survey was conducted March 7-11 among 1,503 adults, including 538 Republican and Republican-leaning voters, before Rick Santorum's victory in two Southern states.

The poll showed Romney leads Santorum 33 percent to 24 percent in the race for the GOP nomination and the opportunity to square off with the Democratic president. Last month, Romney and Santorum were in a statistical tie, A month ago, the two men were in a virtual tie -- Romney at 28 percent and Santorum at 30 percent.

But both Romney and Santorum are running behind Obama in general election matchups. Obama leads Romney by 12 points (54 percent to 42 percent) among all voters and Santorum by 18 points (57 percent to 39 percent).

Sample sizes and the error attributable to sampling shows what would be expected at the 95 percent level of confidence for different groups in the survey, the center said. There was no other margin of error listed.