MANCHESTER, N.H. — Republican presidential candidates called for aggressive steps to curb illegal immigration, seizing on a delicate political issue as more than a dozen White House candidates faced off in New Hampshire on Monday night for a pointed preview of the first full-fledged debate of the 2016 primary season.

All but three of the 17 major Republican candidates for president participated in what was essentially a debate lite, which – unlike Thursday’s nationally televised debate in Cleveland – didn’t have a cut-off for participation.

The candidates focused their criticism on Democrats instead of each other, yet Monday’s meeting offered a prime-time practice round for the party’s most ambitious, who appeared on stage one at a time. They addressed several contentious issues, immigration topping a list that included abortion, climate change and foreign policy.

Former Texas Gov. Rick Perry, who may not qualify for the upcoming formal debate, called the flow of immigrants crossing the border illegally “a serious wound.”

“You want to stanch the flow,” he said as his Republican rivals watched from the front row of the crowded auditorium at St. Anselm College. On those immigrants who have overstayed visas, Perry charged, “You go find ’em, you pick ’em up and you send ’em back where they’re from.”

Former Pennsylvania Sen. Rick Santorum went further, calling for a 25 percent reduction in low-skilled immigrants coming into the country legally.

“Everyone else is dancing around it. I’m going to stand for the American worker,” Santorum declared.

Monday’s group included seven current or former governors, four senators, a businesswoman, a retired neurosurgeon and one former senator. Billionaire businessman Donald Trump, who has dominated the GOP primary in recent weeks, is among the three major candidates who decided not to participate.

Trump, who launched his presidential bid by calling Mexican immigrants rapists and criminals, cited criticism from the local newspaper host, yet he is expected to play a prominent role in Thursday’s formal debate, where only the top 10 Republican candidates – as determined by national polls – will be allowed on stage.

Monday’s event was broadcast live on C-SPAN and local television stations in Iowa and South Carolina – states that, along with New Hampshire, will host the first contests in the presidential primary calendar in February.

The coincided with new developments on politically charged issues.

Just an hour before the 7 p.m. forum was to begin, the Senate blocked a Republican-backed bill to strip funding from Planned Parenthood, reviving a debate on social issues that some Republican officials hoped to avoid in 2016.

Three of the four senators in Monday’s event – Marco Rubio of Florida, Ted Cruz of Texas and Rand Paul of Kentucky – participated via satellite from C-SPAN’s Washington studio so they wouldn’t miss the high-profile vote.

“We had to be here to vote to defund Planned Parenthood,” Cruz said.

It’s a welcome debate for Democrats who see women – married women, particularly – as a key constituency in 2016. Leading Democratic presidential candidate Hillary Clinton, who would be the nation’s first female president, lashed out at the attacks on Planned Parenthood in a web video released before Monday’s forum.

“If this feels like a full-on assault for women’s health, that’s because it is,” Clinton said in the video, criticizing by name former Florida Gov. Jeb Bush, Wisconsin Gov. Scott Walker, and Perry.

Just one woman was on stage Monday night: former Hewlett-Packard CEO Carly Fiorina, who is unlikely to qualify for Thursday’s higher-profile debate.

Democrats are also eager to debate Republicans on immigration.

Republican leaders have acknowledged the need to improve the party’s standing among the surging group of Hispanic voters. Yet while many Democrats favor a more forgiving policy that would allow immigrants who are in the country illegally a pathway to citizenship in many cases, many Republicans focus on border security.

Rubio, once a lead salesman for a comprehensive immigration overhaul, said Americans want the border fence completed and more border security agents before there’s any discussion of what to do with the 11 million immigrants in the country illegally.

Others offered a softer tone on the divisive issue Monday night.

Ohio Gov. John Kasich said “law-abiding, God-fearing” immigrants who are in the country illegally should be allowed to stay. Those who break the law, he said, “have to be deported or put in prison.”

Bush said fixing the nation’s immigration system is a key part of his plan to help the economy grow 4 percent each year. He also called for reducing legal immigration, particularly the number of people allowed to enter the country on family petitions.

President Obama injected another contentious issue Monday when he unveiled new emissions limits on power plants designed to address climate change. He called it a moral obligation and warned anew that climate change will threaten future generations if left unchecked.

Wisconsin Gov. Scott Walker called the move “a buzz saw to the nation’s economy.”

“I want to balance a sustainable environment with a sustainable economy,” Walker said.