Republican presidential hopefuls took the stage in California for their second debate on Wednesday night.

One notable absence from the debate was former US president — and current Republican front-runner — Donald Trump.

The other candidates took to the stage not just to outperform each other, but to try and chip away at Trump's dominant lead.

Trump a no-show

As the debate began, Trump was speaking to workers at a non-unionized auto parts supplier in Detroit days after President Joe Biden joined the picket line of the United Auto Workers union strike.

"They're all job candidates," Trump said of the seven Republicans at the debate. "Does anybody see any VP in the group? I don't think so."

The other Republican candidates criticized Trump's decision not to debate.

"He should be on this stage tonight," said Florida Governor Ron DeSantis, who is second behind Trump in the polls.

"He owes it to you to defend his record where they added $7.8 trillion (€7.4 trillion) to the debt. That set the stage for the inflation we have now."

Christie also accused Trump of hiding "behind the walls of his golf clubs."

"You're ducking these things, and let me tell you what's going to happen. You keep doing that, no one up here is gonna call you Donald Trump anymore. We're gonna call you a Donald Duck," he said, receiving groans from the audience in response.

Candidates spar over migration

The candidates discussed issues ranging from the economy to China, but a tougher stance on immigration took center stage as candidates vied for their break-out moments.

Former New Jersey Governor Chris Christie said he would send the National Guard to the US-Mexico border "on day one" to prevent illegal crossings.

Former South Carolina Governor Nikki Haley, herself the daughter of Indian immigrants, proposed cutting foreign aid to Latin American countries until the border is secured.

"Only when we fix the immigration system, only when we make the border secure should we ever put more money into this," the former United Nations representative said

Former Vice President Mike Pence brought up a Trump-era policy to make asylum-seekers wait in Mexico for US court hearings.

zc/wmr (AP, Reuters, AFP)