In Iowa, Governor DeSantis has managed to hold on to his post-debate gains while other candidates have returned to pre-debate lows in the 2024 GOP presidential nomination horse race. While it could signal a change in trajectory for the governor’s flailing campaign, President Trump has also gained support in the Hawkeye State.

Nationally, the first GOP primary debate proved to be a flash in the pan, with most candidates losing any post-debate polling bumps within days of the event.

In Iowa, though, where voters are preparing for the first in the nation caucus this January, the debate appeared to shake up the race, according to surveys conducted by Public Opinion Strategies and the Citizen Awareness Project, a partisan Republican organization.

The debate sent support for Ambassador Nikki Haley to 11 percent from 3 percent, for one. Businessman Vivek Ramaswamy saw his support slump to 7 percent from 10 percent, the pollster found.

While Ms. Haley and Mr. Ramaswamy have seen their support recede since the debate, falling to 6 percent each, according to the pollster, Mr. DeSantis has maintained a statistically significant gain in the Iowa polls since the debate.

“This is a two-man race in Iowa. Now that the dust has settled after the first debate, Trump and DeSantis are the only two candidates with significant support — nobody else eclipses 6 percent,” the pollster wrote in a memo. “DeSantis saw a significant increase in his ballot standing since before the debate which has stabilized.”

Before the debate, Mr. DeSantis’s support was 14 percent in Iowa. After the debate, it rose to 21 percent. Now, Mr. DeSantis enjoys 22 percent in the state.

The results from the Hawkeye State are a rare bit of good polling news for Mr. DeSantis’s campaign, as he’s been on a downward trajectory in the polls for months and has been struggling to reverse it.

In an attempt to double down on efforts in Iowa and New Hampshire, Mr. DeSantis’s Never Back Down PAC, which has been integral to his presidential election effort, pulled out of some on-the-ground efforts in Nevada and California and ended field operations in North Carolina and Texas in late August.

While it looks as if the redoubling of efforts in these early-voting states might be paying off for the governor, Mr. Trump has also expanded his support.

In the survey, Mr. Trump led with 42 percent support before the debate, held steady at 41 percent support after the debate, and slightly expanded his lead to 45 percent since then.

While these results are within the poll’s plus-or-minus 4.9 percent margin of error, Mr. Trump’s steady lead highlights just how far behind him Mr. DeSantis is in the polls. When Mr. DeSantis was closest to Mr. Trump in the wake of the debate, Mr. Trump still led by 20 points, a far cry from the competitive race that was developing in early 2023.

In FiveThirtyEight’s average of national polls, Mr. DeSantis reached his apex in late February, when he trailed Mr. Trump by 2 points, 40.8 percent to 38.8. Since then, he has been on a downward trend, while Mr. Trump has only consolidated his lead.

While it’s premature to say that Mr. DeSantis has successfully reversed this trend nationally, the tick-up in the polls is good news for the governor, who has stuck to 14.5 percent support nationally compared to Mr. Trump’s 54.1 percent.