Ambassador Nikki Haley’s unfavorable numbers among Iowa Republican voters have jumped in recent months even as she has overtaken Governor DeSantis in the race for second place in the 2024 caucuses. According to the final Des Moines Register poll  released just 48 hours before the caucuses begin, Mrs. Haley barely leads Mr. DeSantis, and President Trump is still running away with first place.

Mrs. Haley’s favorable rating among Iowa Republicans sits at a dismal 48 percent compared to 46 percent unfavorable. For Mr. DeSantis, that split is 58 percent favorable and 36 percent unfavorable. Mr. Trump has the highest approval numbers — 69 percent favorable to 29 percent unfavorable. 

It’s a quick fall for Mrs. Haley, who only in August had a favorable rating of 53 percent and an unfavorable rating of just 26 percent in the state. Some of her supporters, though, have made it clear that Iowa is not do-or-die for the former ambassador. She only has to finish a distant second or even a strong third, they say, in order to give her the momentum to win New Hampshire and then barnstorm and win a surprise victory in her home state, South Carolina on February 24.

The New Hampshire governor, Chris Sununu, who is supporting Mrs. Haley for president, says “she’s the only one with momentum” headed into the first caucuses and primaries. “Naturally, she’s going to get enough of a bump with the voters” as New Hampshire primary day approaches, Mr. Sununu told CNN. 

On Sunday, the former Maryland governor, Larry Hogan, echoed those sentiments and endorsed Mrs. Haley, saying she was the only Republican candidate with the “momentum” to beat Mr. Trump after Iowa. 

A former congressman and presidential candidate, Will Hurd, told USA Today that Mrs. Haley, whom he is supporting, is beating expectations in Iowa and could win the Granite State in an upset. “She’s been doing better in Iowa than anybody thought at the beginning of the campaign,” Mr. Hurd said. “She’s through the roof in a place like New Hampshire, and that’s what’s really starting this broader momentum.”

One of Mrs. Haley’s biggest New York fundraisers, Eric Levine, says her campaign does not depend on Iowa the same way Mr. DeSantis’ campaign does. “The most pressure is on DeSantis,” Mr. Levine told Fox News. “If he finishes third, he’s done. Nikki Haley doesn’t have that pressure on her. She just needs to finish strongly. She’s competing in New Hampshire, she’s competing in South Carolina, she’s got a shot at winning both those states.”

The former president did win an endorsement on Sunday from North Dakota’s governor, Doug Burgum, who became the first 2024 GOP presidential contender to support Mr. Trump. Mr. Burgum dropped out of the race in December.

Mrs. Haley still faces an enthusiasm gap, however. In Iowa, the former president has the most solid base of support, with 82 percent of those who plan to support him saying that their mind is made up and they will not consider another candidate. For Mrs. Haley, 37 percent of her supporters say they could be persuaded to caucus for someone else. Among Mr. DeSantis’ supporters, 35 percent say they are open to changing who they will caucus for. 

Mr. Trump’s likely caucus supporters are also by far the most enthusiastic about showing up on Monday, which is expected to be the coldest caucus day in history with temperatures dropping well below zero and wind chills even lower still. 

Among the former president’s supporters, 88 percent say they are either “extremely” or “very enthusiastic.” For Mrs. Haley, that enthusiasm number is only 39 percent, and only 62 percent of Mr. DeSantis’ supporters say they are enthusiastic. 

Another problem for Mrs. Haley is that her supporters in Iowa have been the most transient, with more than half of her current caucus goers saying they at one point supported another candidate. For Mr. Trump, 87 percent of his current supporters say he was always their first choice to be the Republican nominee.