COLUMBUS, Ga. (AP) — The Republicans running for Georgia's open U.S. Senate seat took aim at each other's records and experience in a debate Saturday, with the three congressmen in the race facing criticism over their time in Washington.

The Republican primary fight has been closely watched nationally, with Republicans needing six seats to claim a majority in the U.S. Senate. Republicans can't afford to lose the seat, which opened when Republican Sen. Saxby Chambliss announced plans to retire.

The Georgia GOP primary is May 20.

Former Secretary of State Karen Handel and former Dollar General CEO David Perdue have been battling each other as outsiders, and both set their sights on the three congressmen in the race — Reps. Paul Broun of Athens, Phil Gingrey of Marietta and Jack Kingston of Savannah.

"I have a track record of standing up for my conservative principles at great cost," said Handel, who fought a public battle with Planned Parenthood when she was an executive with the breast cancer charity, Susan G. Komen for the Cure. "The three congressmen, they have had every opportunity to do all the things they say they want to do."

Perdue added Handel, who ran for governor in 2010, to his list of career politicians and said they have had every opportunity to make a difference and haven't done so.

"If you like what is going on in Washington, you've got four good politicians to choose from," Perdue said. "If you want different results in Washington, you need to send someone different to Washington."

The congressmen pushed back, arguing that they have been fighting against Washington the whole time they have been in office.

Kingston, who has been leading in fundraising, said he has one of the most conservative voting records.

"I have to ask, where have some of these people been?" Kingston said. "I've been a soldier in the battle for a long time, and I will continue to fight."

Kingston also took a direct swipe at Perdue, who has been leading in the polls. He noted Perdue had sought and didn't receive the backing of the U.S. Chamber of Commerce despite his business background. The chamber backed Kingston and has spent about $920,000 in TV and online ads supporting him.

"If someone's business record is so good and so complete, perhaps they're concerned about some of the shady business dealings and some of the layoffs and some of the golden parachutes," Kingston said, drawing some boos from the crowd.

The reference was apparently to Perdue's time at the helm of Pillowtex Corp., a North Carolina textile company that closed just three months after he left in what was then the single largest job loss in that state's history. Perdue spent eight months at Pillowtex, but they came at a critical crossroads for the company. When he took over in July 2002, the company had recently emerged from Chapter 11 bankruptcy.

For his part, Perdue has called what happened at Pillowtex a tragic situation and said he went there to try to help. Soon after he arrived, the company's owners decided to sell the company.

Gingrey dismissed the criticism from Perdue and Handel, saying he's been frustrated by voting repeatedly against bad legislation. He noted he practiced medicine for 32 years while serving in Congress for 11 years.

"I am a professional physician. I'm not a professional politician," Gingrey said.

Broun, also a doctor, said he can't be lumped in with the other congressmen because he has the stronger record of voting against big government and noted he voted against Rep. John Boehner as speaker.

"Everything they say they will do, I've done," Broun said. "I've been fighting for liberty and freedom."

Also on the GOP ballot are patent attorney Art Gardner and network engineer Derrick Grayson.

Democrat Michelle Nunn, daughter of former Sen. Sam Nunn, is the front-runner to advance in her May 20 primary.