A day ahead of the last GOP primary debate in Iowa and less than a week before the Iowa caucuses, Ambassador Nikki Haley is biting at Governor DeSantis’s heels in the polls there. Recent polling in New Hampshire, though, is raising questions about the accuracy of those primary polls.

A new Morning Consult survey conducted between January 1 and 7 found that Ms. Haley has overtaken Mr. DeSantis in the competition for second place in the Hawkeye State. President Trump is the clear favorite.

The survey found that Ms. Haley has 15 percent support and Mr. DeSantis has 14 percent, within the survey’s margin of error. Mr. Trump enjoys majority support among Republican respondents at 58 percent. 

While the Morning Consult survey is the first survey of Iowans since the holidays, other polls had shown Ms. Haley trending upward in the state ahead of the break.

A December 19 InsiderAdvantage survey, for one, showed Ms. Haley and Mr. DeSantis tied at 17 percent. Mr. Trump enjoyed 49 percent support at the time.

On Wednesday, Ms. Haley and Mr. DeSantis will have what is potentially their last, best chance to get in front of voters on a major stage before the caucuses next week. 

The debate will be held at Drake University at Des Moines and is being hosted by CNN. It is scheduled to begin at 8 p.m. Central. Mr. Trump will not be in attendance and is instead scheduled to appear at a Fox News town hall at the same time.

Mr. DeSantis has attacked Mr. Trump for refusing to appear at the debates, telling reporters in December: “He’s not willing to come here and answer questions.”

“He parachutes in for 30-, 45-minute, hour speeches and then just leaves, rather than listening to Iowans, answering questions, and doing, I think, what it takes to win,” Mr. DeSantis said.

Ms. Haley has likewise said that “it’s time for Donald Trump to show up,” in a post on X, adding: “As the debate stage continues to shrink, it’s getting harder for Donald Trump to hide.”

While Iowa looks increasingly locked up for Mr. Trump, the candidates there are vying to try and beat expectations in the caucuses. A revered pollster in Iowa, Ann Selzer, said in an interview with FiveThirtyEight that the next week is when candidates will pull out all the stops in Iowa.

“Between now and caucus night is when all the cards get thrown on the table,” Ms. Seltzer said. “I say that the world wakes up on January 2 with a January 15 caucus and suddenly there’s an urgency and an immediacy.”

Ms. Seltzer pointed to Senator Santorum’s meteoric rise in Iowa in 2012, when he moved from single-digit support in the polls to become the winner of the Iowa caucuses.

The candidate who has bet the most on a good performance in Iowa, Mr. DeSantis, has invested significant resources into producing what he hopes will be a come-from-behind victory like Mr. Santorum’s.

The main strategy for Never Back Down, a PAC that does much of Mr. DeSantis’s ground work, has been to invest heavily in a door-knocking campaign — $100 million to be exact. 

In late December the group claimed to have knocked on 812,000 doors in Iowa, a state with about 3.2 million residents.