A survey by the Des Moines Register/Bloomberg Politics
released Saturday night has the real estate mogul capturing 23% of the vote among likely Republican caucusgoers in the critical early voting state, but Carson is at 18%.
And when first and second place choices are combined, they are even at 32%.
Both Trump and Carson have benefited from anti-establishment sentiment among voters in the Hawkeye State. Neither man has held elected office, and both scored well among Christian conservatives, the poll found.
Trump has established himself as the dominant Republican candidate
in other Iowa surveys and in nationwide polls. He's also been quietly building an Iowa operation
, and has made six trips to the state since declaring his candidacy in June.
His favorability ratings among likely GOP caucusgoers stand at 61%, but 35% of those surveyed have an unfavorable view of him. But that's a sharp improvement from the last Des Moines Register/Bloomberg Politics poll in May -- before Trump announced his candidacy -- which found his favorable/unfavorable ratings at 27% and 63%, respectively.
He's polling most strongly among those who are first-time likely caucusgoers and tea party activists, the survey found.
Carson, meanwhile, has a 79% positive rating.
Scott Walker, once the GOP's leader in Iowa, is tied for third with Ted Cruz at 8%. Jeb Bush and Marco Rubio are next at 6%, with Carly Fiorina (5%) in fifth place and Mike Huckabee and Rand Paul (4%) tied for sixth.