NASHVILLE (AP) - An exit poll of voters in Tennessee's presidential primary revealed Rick Santorum beat Mitt Romney on Tuesday thanks to strong support among born-again Christians - about three-quarters of those who went to the polls on Tuesday.

Santorum also led Romney by more than 3-to-1 among those who said it mattered a "great deal" that a candidate shared their religious beliefs.

Mary Cecil, a retiree voting in Sevierville, said she was concerned about the economy, but the deciding factor in casting her vote for Santorum was: "I would like to have a true Christian in the White House."

With 98 percent of precincts reporting, Santorum had 37 percent of the vote to Romney's 28. Newt Gingrich received 24 percent and Ron Paul got another 9 percent.

Santorum led Romney by 14 percentage points when voters were asked which candidate best understood the problems of average Americans, according to an exit poll conducted by Edison Res earch for The Associated Press.

The former Pennsylvania senator had a more than 2-to-1 lead over Romney among voters who considered themselves "very conservative." He also led Romney by 14 percent points among voters who supported the tea party. Romney led among voters who considered themselves "moderate."

Half of those voting in Tennessee's Republican presidential primary said the economy was their top concern, with another third citing the deficit, but no candidate had a significant lead among those voters.

David Morgan, a 55-year-old salesman voting in Nashville listed his top concerns as "the economy and jobs and now the gas prices."

"The whole economy is down," he said. "Myself, I don't make as much as I used to."

Morgan said he voted for Mitt Romney.

"I feel like he is the one that can beat Obama," he said.

Many voters agreed with him.

Romney, the former Massachusetts governor, led Santorum by 18 percentage points when vot ers were asked which candidate had the best chance of beating President Barack Obama. More than a third of Republican voters said beating Obama was the candidate quality that mattered most to them when asked to pick among four choices that included moral character, experience and being a "true conservative."

Only 11 percent of voters said abortion was the most important issue to them, but those voters favored Santorum over Romney by a margin of 5 to 1.

Both Santorum and Gingrich were strongly favored over Romney by those voters who said government experience best prepares a candidate to serve as president, with Santorum slightly ahead. Santorum and Romney were favored equally by those who said experience in business was most important.

Results from the Tennessee exit poll are based on interviews with 2,530 Republican primary voters, including 640 absentee or early voters who were interviewed by phone before election day. Election day voters come from a rando m sample of 30 polling places. The poll has a margin of sampling error of plus or minus 3 percentage points.