Former Florida Governor Ron DeSantis and former South Carolina Governor Nikki Haley traded barbs and fended off attacks from Viveck Ramaswamy and former New Jersey Governor Chris Christie in the final Republican presidential debate ahead of the crucial Iowa caucuses.

DeSantis and Haley were battling for second place behind former President Donald Trump, while Ramaswamy and Christie tried to stay relevant before voters start casting their ballots next month.

Haley has been gaining ground in the polls and was the target of frequent attacks from DeSantis and Ramaswamy. Early on, DeSantis said that Haley "caves anytime the left comes after her," while Ramaswamy accused her of being corrupt for taking a job with Boeing after serving as the U.S. ambassador to the United Nations.

Haley brushed off the attacks and defended her record as governor of South Carolina and in the United Nations. She also touted her recent endorsement from Americans for Prosperity Action.

"When it comes to these corporate people that want to suddenly support us, we'll take it, but I don't ask them what their policies are. They ask me what my policies are, and I tell them what it is. Sometimes they agree with me, sometimes they don't," she said.

"In terms of these donors that are supporting me, they're just jealous," Haley said.

Christie criticized the candidates for ignoring Donald Trump and also defended Haley against some of Ramaswamy's attacks.

"He has insulted Nikki Haley's basic intelligence. Not her positions, her basic intelligence," he said, adding, "Look, if you want to disagree on issues, that's fine. Nikki and I disagree on some issues. I've known her for 12 years ... and while we disagree about some issues and we disagree about who should be president of the United States, what we don't disagree on is this is a smart accomplished woman. You should stop insulting her."

Christie also attacked DeSantis for refusing to give straight answers to several questions throughout the night.

"You have to be willing to offend with the truth and answer the question: fit or unfit," Christie said.

At Home with Gary Sullivan