Provo • As his two Republican competitors criticized him, Provo Mayor John Curtis gripped the podium a little tighter and grinned.

The attacks against him started midway through a Friday night debate — the second in the GOP primary race to replace former Rep. Jason Chaffetz. Utah County businessman Tanner Ainge took the first shot. And former state Rep. Chris Herrod piled on from there.

They blasted Curtis for being a registered Democrat about 20 years ago. They condemned him as being a flimsy and willing-to-fold conservative now. And they accused him of raising taxes during his eight years as mayor.

"I'm a little bit concerned about my opponent John Curtis," Ainge said in response to a question about bridging the divide between Republicans and Democrats in Congress. "While I think it's important to work together, I don't think you actually have to switch sides to do it."

Herrod quickly backed Ainge, saying it frustrates him "when people say they're conservative but their actions are not."

Their feisty comments were met by a nearly even mix of cheers and boos from the crowd of about 300 people. Curtis defended himself with a joke and a list of his values: liberty, personal responsibility, accountability and family values.

"Like Jason Chaffetz, like Ronald Reagan and Donald Trump, I once had a fling on the dark side," he said, referring to his former Democratic leanings. "That was 20 years ago, and I've never looked back. Some people will never forgive me for that."

His staff also responded by circulating papers among members of the media with a comment from Utah Gov. Gary Herbert, who has endorsed Curtis and denounced the other candidates for negative campaigning.

The heated exchanges quickly overshadowed the candidates' responses on health care, Russia and public lands — topics the three gave nearly identical answers to. After posing a question on education, Jennifer Napier-Pearce, Salt Lake Tribune editor and co-moderator of the debate, even teased: "I anticipate similar themes in your responses."

For most of the hourlong event, hosted by The Tribune and the Hinckley Institute of Politics, that was the case. The biggest difference came in the response from the audience. Curtis consistently received the loudest applause — the event was held on his home court at Provo's Utah Valley Convention Center.

He also has the early lead in the primary. The latest Tribune-Hinckley Institute poll shows Curtis trouncing his competitors by a more than 2-to-1 margin — with 37 percent of support — among Republicans registered to vote.

Smaller spats broke out over taxes and immigration. Herrod bashed Provo for being a "sanctuary city" and not complying with immigration enforcement. Curtis rebutted, saying there's "at least 100 police officers that would be extremely offended to hear Provo be called a sanctuary city. … I am proud to say that we are not a sanctuary city, and I would not condone that in Provo."

Curtis didn't abstain from lobbing barbs.

After Ainge, who has not held elective office, declared that he's "the only one who hasn't raised taxes," the mayor had a quick, sarcastic reply: "Tanner, we're so proud of you." At the end of the debate, Curtis shook it off as a "fun moment."

Ainge, meanwhile, stood by his remarks about Curtis' party loyalty and called his opponent a "good guy."

"Mayor Curtis has a record," he said. "I think it's important for people to know."

Some in the audience weren't so quick to brush off the negative comments. Kim Snelson, a Provo resident who supports Curtis' run, believes Ainge went too far and "tried to make a nonissue an issue."

"He used it as his personal platform to attack John Curtis," she said.

Herrod gained support this week from a well-funded political action committee, National Horizon, which spent $96,000 on negative mailers targeting Curtis — mocking the mayor's casual dress, among other things. Herrod cannot legally communicate with the PAC and disparaged it for going after "petty things." He, too, though said Curtis' history as a Democrat is fair game.

Though debate on the remaining topics was tame — mirroring another 3rd Congressional District debate held earlier this month — each candidate found opportunities to stand out.

All three rebuked the Senate's failed efforts to repeal the Affordable Care Act this week, but Curtis offered perhaps the strongest and most colorful disapproval. He suggested Republicans weren't ready with a plan and "moved too quickly" with the bill they put together. He described Obamacare as "a nightmare that just keeps recurring over and over again." And he proposed drafting alternative legislation rather than unsuccessfully trying to "put Humpty Dumpty back together again."

Herrod, who worked on Republican Sen. Ted Cruz's 2016 presidential campaign, seemed to align the most with President Donald Trump, saying he "absolutely" supports his travel ban and a wall between the United States and Mexico. He also proposed abolishing the Department of Education and seeking Russia's help in dealing with North Korea.

Ainge backed cutting federal spending and allowing individuals to use pretax dollars to pay for health insurance premiums. He stands with Mitt Romney — and was a volunteer for his 2008 bid — saying the GOP presidential contender was "proven right" when he called Russia the United States' No. 1 "geopolitical foe."