Haley and DeSantis quickly tear into each other's records in their head-to-head Republican debate

"We don't need another mealy-mouthed politician who just tells you what she thinks you want to hear, just to try to get your vote and then to get in office and to do her donors' bidding," DeSantis said in an early barb.

"He's upset that his campaign is exploding," Haley said in her reply.

The former U.N. ambassador directed viewers to a website her campaign created chronicling what she said were DeSantis' lies. The Florida governor in turn tried to send people to his website, where he said he collected "all the greatest hits" of Haley's false statements.

Standing at lecterns an arm's length apart, DeSantis and Haley both sought a strong debate performance without lower-polling rivals in Iowa to lift their campaigns in the final days before Monday's caucuses, where a good showing could provide much-needed momentum as each tries to become the primary alternative to Donald Trump.

The former president and GOP front-runner skipped the CNN debate in Des Moines to appear in a Fox News town hall in the same city.

Neither Haley nor DeSantis answered directly a question about whether Trump "has the character to be president."

"His way is not my way," Haley said. "I don't have vengeance. I don't have vendettas. I don't take things personally."

DeSantis said Trump failed to deliver on his promises to build a border wall and make Mexico pay for it, prosecute Hillary Clinton, "drain the swamp" or eliminate the national debt.

"We need to deliver and get this stuff done," DeSantis said.

Hours before Haley and DeSantis took the stage, New Jersey Gov. Chris Christie announced he will drop out of the race, a curveball with major implications. Christie, by far the most aggressive Trump critic running for the GOP nomination, faced intense pressure to step aside so opponents of the former president could unify behind a single candidate and improve the odds of dethroning front-runner Trump.

Christie, along with biotech entrepreneur Vivek Ramaswamy, did not qualify for Wednesday's debate after appearing in earlier events.

Wednesday's debate is especially important for Haley, a politician long known for her disciplined approach to messaging. That reputation has been tested recently after a series of gaffes, including her failure to mention slavery as the root cause of the Civil War and a quip that New Hampshire voters will have a chance to "correct" the results that emerge from Iowa.

The debate offers Haley a chance to reset a campaign that has come under fresh scrutiny by everyone from her GOP rivals to President Joe Biden, a sign that her opponents in both parties see her as a rising contender.

Though both DeSantis and Haley are trailing Trump in polls, the candidates spent much more time criticizing each other Wednesday than focusing on the front-runner.

Each tried to take the position as the leader who would address the U.S.-Mexico border and the strain of record-high numbers of migrants crossing.

DeSantis noted his state chartered a flight to fly migrants from Texas to Martha's Vineyard, Massachusetts, without notifying local officials. He also pledged to finish building the border wall Trump made central to his presidency and accused Haley of being insufficiently supportive of it.

Haley pointed to her actions as South Carolina's governor, noting she passed a law requiring businesses to check the immigration status of employees and job applicants and a law requiring local police to inquire about the immigration status of people they stop. The latter drew a lawsuit from the U.S. Justice Department during the administration of former President Barack Obama — something Haley noted with pride.

The central role the U.S. is playing in the war in Ukraine and the Israel-Hamas war emerged as a clear dividing line between Haley and DeSantis.

Haley offered a passionate defense of sending aid to Ukraine and Israel. DeSantis charged that she was more concerned about the Ukrainian border than the southern border of the United States.

"You can take the ambassador out of the United Nations, but you can't take the United Nations out of the ambassador," DeSantis jabbed.

Haley punched back. "This is about preventing war," she said. "You only do that when you focus on national security, not telling lies to the American people that they have to choose. That is wrong."

Many expected caucusgoers said they planned to pay close attention to a debate featuring Trump's main opponents.