NASHVILLE (AP) - Early voting for Tennessee's Super Tuesday presidential primary is under way, with Republican leaders lining up behind their respective choices for the nomination.

Voters began casting ballots Wednesday, and early voting runs through Feb. 28. Tennessee is among 10 states holding their presidential primaries March 6.

"We're going to have a race here," said state Republican Party Chairman Chris Devaney. "I think we're going to have a strong showing, because people are concerned about the direction of the country."

"It's a healthy thing for our party to have this debate," he said.

Gov. Bill Haslam and House Speaker Beth Harwell are among a large number of state Republican leaders backing former Massachusetts Gov. Mitt Romney.

"One thing this campaign has shown is that it's a very volatile Republican electorate right now," Haslam said.

"You've seen several people come up and be the challenger," he said. "But I think the one consistent has been that Romney has been the person they've been challenging."

Harwell said she's pleased with all the contenders in the GOP primary.

"Whoever comes out of the Republican primary I'll be 100 percent behind," she said. "Obviously, I've endorsed Mitt Romney, but that's not to say anything bad about any of the others."

Former House Speaker Newt Gingrich's state leadership team includes state Sen. Stacey Campfield of Knoxville and Rep. Tony Shipley of Kingsport, while former U.S. Sen. Rick Santorum's state effort is led by tea party activist Kay White of Johnson City.

White said she's been working on setting up a statewide network of volunteers and has been encouraged by the number of college-age people interested in getting involved in the Santorum campaign.

"This is very heartwarming for me and everybody that our young people are coming alive," she said.

Senate Speaker Ron Ramsey was an early supporter of Rick Perry, but has declined to endorse any of the remaining candidates since the Texas governor dropped out of the race.

"I think it will be between Santorum and Romney now, I think Newt's pretty much out of it," Ramsey said. "But I'll just make up my mind when I walk into the voting booth."