Seven Republicans vying for nomination as the party's presidential candidate for next year's United States election struggled to shore up voter support in their second primary debate Wednesday night in California, according to political analysts from major TV networks.

CNN reported that the absent front-runner, former President Donald Trump, remains dominant after his rivals took potshots at him and clashed among themselves at the Ronald Reagan Presidential Library.

Fox News, whose affiliate Fox Business co-moderated the debate with Univision, reported that Florida Governor Ron DeSantis won the debate, though the second runner-up still trails Trump by a big margin.

Trump's legal troubles have done little to dent his lead, with 59 percent of Republican primary voters in a new NBC News poll making him their top choice, with DeSantis a distant runner-up at 16 percent.

DeSantis criticized Trump for his absence, so did former New Jersey Gov. Chris Christie who called the ex-president Donald Duck for ducking the debate.

Trump, who is battling multiple criminal cases, has decided to skip the debates, and instead met auto industry workers in the battleground state of Michigan.

Former South Carolina Gov. Nikki Haley clashed with DeSantis and entrepreneur Vivek Ramaswamy.

Some of the debaters, who included former vice president Mike Pence, South Carolina Senator Tim Scott and North Dakota Governor Doug Burgum, also took a swipe at President Joe Biden for his immigration policy.

The fractious debate saw the candidates regularly shouting over one another. They were divided over the war in Ukraine, with Christie, Scott and Pence defending US support for Kyiv, in contrast with skepticism from DeSantis and Ramaswamy.

The Biden campaign offered a withering perspective on the policy proposals aired over the two-hour scuffle, especially on border control.

"Not one person on that stage is serious about enacting meaningful immigration reform, and it shows," spokesperson Kevin Munoz said in a statement.