Former President Donald J. Trump still has a huge lead in Iowa, according to a poll released Monday, but Nikki Haley has surged to tie Gov. Ron DeSantis of Florida for a distant second place.
Mr. Trump has the support of 43 percent of voters likely to participate in Iowa’s first-in-the-nation Republican caucuses in January, the new Des Moines Register/NBC News/Mediacom poll found — about the same as the 42 percent he had in the same poll in August.
Mr. DeSantis and Ms. Haley, the former governor of South Carolina and former United Nations ambassador, are tied at 16 percent. That is a decline of three percentage points for Mr. DeSantis and an increase of 10 points for Ms. Haley, driven in part by increasing support for Ms. Haley among independent voters.
The poll was conducted by J. Ann Selzer and has a margin of error of plus or minus 4.9 percentage points.
Behind Ms. Haley and Mr. DeSantis are Senator Tim Scott of South Carolina at 7 percent, the entrepreneur Vivek Ramaswamy and former Gov. Chris Christie of New Jersey at 4 percent, and Gov. Doug Burgum of North Dakota at 3 percent. None of those candidates have moved significantly since the August poll.
The new survey was conducted before former Vice President Mike Pence dropped out of the race on Saturday. He had only 2 percent support — down from 6 percent in August — and his supporters were redistributed to their second-choice candidates in the final results.