MILWAUKEE (AP) — The Republican presidential candidates vying to be the leading alternative to front-runner Donald Trump tangled on abortion at the first Republican primary debate Wednesday night, underscoring the party's challenges on the issue after the Supreme Court overturned Roe v. Wade last year.

All of the candidates identified as "pro-life," but differed on when restrictions should kick in after the court ended the constitutional right to an abortion, leading to a wave of restrictions in Republican-led states.

Florida Gov. Ron DeSantis, who is polling a distant second Trump, refused again to say whether he supports a federal ban.

"I'm going to stand on the side of life. Look, I understand Wisconsin is going to do it different than Texas. I understand Iowa and New Hampshire are going to be different, but I will support the cause of life as governor and as president," he said.

Former U.N. Ambassador Nikki Haley again argued for consensus on the issue, arguing passing a federal ban would be highly unlikely without more Republicans in Congress.

"Consensus is the opposite of leadership," rebutted former Vice President Mike Pence, who has made his opposition to abortion rights a central tenant of his campaign. Pence supports a federal ban on abortion at six weeks, before many women even know they're pregnant, and has called on the field to back a 15-week national ban as a minimum.

Trump wasn't on stage in Milwaukee but was expected to be a central figure nonetheless. Fox News moderators Bret Baier and Martha MacCallum were expected to press his rivals to articulate how they would differ in style and substance from the former president, who holds a commanding early lead in the race.

With less than five months until the Iowa caucuses jumpstart the GOP presidential nomination process, the debate is a critical opportunity for lower-polling candidates to introduce themselves to millions of voters, many of whom are just beginning to pay attention to the race. The pressure is greatest for DeSantis who announced his campaign in May to great fanfare but has since struggled to gain traction and is now fighting to maintain his distant second-place status.

Also on stage were South Carolina Sen. Tim Scott, former Arkansas Gov. Asa Hutchinson and North Dakota Gov. Doug Burgum, who was hospitalized after hurting his Achilles tendon but chose to participate nonetheless.

The primetime event was unfolding at a moment of reckoning for the Republican Party.

Trump is the prohibitive early front-runner in the race, raising serious questions about whether the party will have much of a competitive primary. Yet Trump's vulnerabilities in a general election are clear, particularly after four criminal indictments that charge him with hoarding classified documents, conspiring to overturn the 2020 election and making hush money payments to a porn actor and other women.

On Thursday, Trump is set to travel to Georgia to be booked again on criminal charges.

Yet Trump's standing in the primary has only increased as the charges have mounted, leaving the GOP on track — barring a stunning realignment — to nominate a candidate who would enter the race against President Joe Biden, a Democrat, in a potentially weak position. Polling this month from The Associated Press-NORC Center for Public Affairs Research found 64% of Americans are unlikely to support Trump if he is the GOP nominee, including 53% who say they would definitely not support him and 11% who say they would probably not support him in November 2024.

While DeSantis, who is running a distant second to the former president, had expected to be the top target as the front-runner on the stage, the candidates focused their early attacks on tech entrepreneur Vivek Ramaswamy, who has been rising in the polls.

"Now is not the time for on-the-job training. We don't need to bring in a rookie. We don't need to bring in people without experience," said Pence, tried to position himself as the most experienced man in stage

Former New Jersey Gov. Chris Christie, who has emerged as a fierce critic of Trump, also laced into Ramaswamy.

"I've had enough already tonight of a guy who sounds like ChatGPT standing up here," he said, calling him an "amateur."

"Give me a hug just like you did to Obama," Ramaswamy shot back — a reference to Christie's embrace of the former president after a storm ravaged his state.

Haley, the only woman on stage, tried to rise above the fray.

"If you want something said, ask a man, if you want something done, ask a woman," she said.

The debate was being held at the Fiserv Forum in downtown Milwaukee, the arena that is home to the Milwaukee Bucks basketball team. The city will also be the site of next summer's Republican convention, a sign of the state's premier battleground status.

The Republican National Committee had set polling and donor thresholds and required participants to sign a loyalty pledge in order to qualify.

Trump had long said he felt it would be foolish to participate, given his dominant lead in the race.

His decision to boycott was nonetheless a blow to the network, which had wooed him privately and publicly to appear. Instead, Trump pre-recorded an interview with ex-Fox host Tucker Carlson that was posted to the platform formerly known as Twitter right before the debate kicked off as counter-programming.

"Do I sit there for an hour or two hours, whatever it's going to be, and get harassed by people that shouldn't even be running for president? Should I be doing that at a network that isn't particularly friendly to me?" Trump said in the 46-minute interview.

"I'm going to have all these people screaming at me, shouting questions at me, all of which I love answering, I love doing. But it doesn't make sense to do them so I'm taking a pass," he said.

___ Colvin reported from Washington and Cooper from Phoenix. Associated Press writers Steve Peoples and Michelle Price in New York contributed to this report.