GOP presidential candidate and retired neurosurgeon Ben Carson has surpassed general front-runner Donald Trump among likely Republican voters in Iowa, according to a Quinnipiac University poll published Thursday.
The retired neurosurgeon leads the 15-candidate Republican field with 28 percent of support in the state, followed by the real estate mogul with 20 percent. In a September Quinnipiac poll of Iowa voters, Trump led with 27 percent and Carson trailed in second place with 21 percent.
Iowa is significant for campaigns because it holds the first major electoral event of the nominating process in the presidential election for both parties. The first votes of the campaign will be cast there on February 1.
Carson leads Trump 33 percent to 13 percent among women in Iowa; men are divided, with 25 percent favoring Carson and 24 percent backing Trump.
Related: Dr. Ben Carson's Life Story Rests on a Deep Adventist Faith
Thirty-percent of likely GOP voters in Iowa said they "would definitely not support" Trump for the Republican nomination. Former Florida Governor Jeb Bush is No. 2 on the "no way" list with 21 percent.
"It's Ben Carson's turn in the spotlight," Peter Brown, assistant director of the poll, said in a statement.
For the candidate with strong leadership qualities, though, Trump leads Carson 80 percent to 76 percent, according to the poll.
Following Carson and Trump is U.S. Senator Marco Rubio from Florida, who placed third with 13 percent, up 8 percentage points from last month. U.S. Senator Rand Paul of Kentucky had 6 percent of support, followed by Bush and businesswoman Carly Fiorina with 5 percent. No other candidate has more than 3 percent of favorability in Iowa.
The poll was conducted between October 14 and 20 among 574 likely GOP voters in Iowa. The margin of error was plus or minus 4.1 percentage points.
Carson has been campaigning steadily in the last few months to catch up to Trump. In a Monmouth University poll released in September, he tied the businessman in Iowa with 23 percent. The ranking marked the first time Trump hadn't led outright in one of the four early primary states of Iowa, Nevada, New Hampshire and South Carolina.
Related: With Soft-Spoken Style, Ben Carson Catches Donald Trump in Iowa
The top-polling Republican candidates will face off in their party's third presidential debate next week at the University of Colorado in Boulder.
Wisconsin Governor Scott Walker and former Texas Governor Rick Perry both recently dropped out of the Republican race, dropping the GOP field to 15 candidates.
