Republican candidates vowed to crack down on crime and close the southern US border as they assailed GOP frontrunner Donald Trump for skipping the party’s presidential second debate.

“He said he was gonna build a wall across the whole border, he got 52 miles,” said former New Jersey Governor Chris Christie at the second GOP presidential debate from the Ronald Reagan Library in Simi Valley, California.

Trump vowed to build a wall across the US-Mexico border but failed to accomplish that in office. At Wednesday’s debate, his rivals for the nomination seized on that failure and blamed President Joe Biden for a migration crisis that has seen crossings across the southern border surge and which polls show is a prominent concern for Republican voters.

Former UN Ambassador Nikki Haley said the US should practice “catch and deport” not “catch and release” with migrants.

The candidates on stage cast the border crisis as part of a larger disorder they say has festered in American communities, targeting growing concerns about crime in US cities.

Florida Governor Ron DeSantis said he and his wife had met three people in Southern California who had been mugged, as he called for “law and order over rioting and disorder.”

The border crisis and immigration is also at the center of a spending fight in the House, where Speaker Kevin McCarthy is struggling to find the votes to keep funding the government and avoid a shutdown this weekend. Hardline conservatives have sought changes to immigration and border policies that are unacceptable to Democrats and the White House and are pushing for deeper cuts to federal spending.

Candidates largely panned the prospect of a shutdown.

“Only when we fix the immigration system, only when we get the borders secure should we ever put any more money into this,” Haley said.

Wednesday saw seven candidates take the stage as Trump continued his boycott of the GOP debates, instead addressing striking auto workers in Michigan.

DeSantis, the top challenger to Trump, didn’t even speak until 16 minutes into the debate and in a largely chaotic forum struggled to be heard. The gathering is most critical for DeSantis after an underwhelming first debate.

DeSantis initially focused his attack not on Biden but on Trump, saying the former president should be at the debate to defend his policies in office and castigating his record on the debt for fueling inflation.

Each candidate sought a break-out moment to distinguish themselves from a crowded field and appeal to voters and donors looking for an alternative to Trump.

Ramaswamy, who raised his profile at the first debate, found himself attacked by multiple rivals on stage.

“Honestly every time I hear you I feel a little bit dumber from what you say,” Haley told Ramaswamy, criticizing plans to expand the use of Chinese-owned TikTok to reach younger voters. “We can’t trust you.”

Haley is looking to maintain momentum in the polls after a strong showing in last month’s debate, when she also hammered Ramaswamy over his lack of foreign policy experience. The two candidates are close in the polls and both seeking to break away from the rest of the GOP pack.

Pence seized on the spending fight in Congress to criticize DeSantis, who also served in the House like the former vice president. Pence said he was more successful at cutting government spending when he was in office than DeSantis had been.

Pence also delivered a jab at Ramaswamy who said he had decided to stop doing business with China in 2018.

“Right around the time that you first started voting,” said Pence about the first-time candidate and political neophyte.

The candidates blasted Biden’s handling of the United Auto Workers strike, using the labor strife targeting Detroit’s Big Three automakers to criticize his economic agenda.

“Bidenomics has failed,” former Vice President Mike Pence, who said Biden’s clean-energy push, which is at the center of the dispute between the UAW and US automakers, is benefitting China at the expense of American workers. “Joe Biden doesn’t belong on the picket line he belongs on the unemployment line.”

The debate comes a day after Biden in a historic show of support for the UAW visited a picket line in Michigan. But Biden’s own policies, in particular a push to electric vehicles have the union and automakers at odds, with organized labor worried the transition will cost union jobs and lower wages.

“If I was giving advice to those workers, I would say go picket in front of the White House in D.C.,” entrepreneur Vivek Ramaswamy said.