Dr. Ben Carson tied Republican front-runner Donald Trump in a new poll of likely Iowa Republicans on Monday, marking the first time any other GOP 2016 contender has managed to rival the real estate mogul at the top slot.

The famed pediatric neurosurgeon could not be less like Trump: he’s soft-spoken where Trump is bombastic and anecdotal where Trump is broad and sweeping, but both occupy a similar space in the political sphere. Neither man has ever been elected to public office, but they’re both famous – Trump for his wealth and Carson for his rags-to-riches personal story – and possess the kind of charisma that’s worth its weight in gold in politics.

The Monmouth University survey found Carson and Trump tied for first place with 23% of likely Iowa Republican caucusgoers. Coming up behind them is another political outsider, former Hewlett Packard CEO Carly Fiorina, who enjoys much of the same appeal as the headliners. Of the candidates who have been elected or held office who make a decent showing – Sen. Ted Cruz and Gov. Scott Walker – neither score double digits.

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The survey found that Trump’s supporters are more certain than Carson’s, but his rise in Monmouth’s first poll since the first presidential debate signals that the unlikely candidate may have significant room for growth.

The survey also found that Carson enjoys far higher likeability ratings than Trump: 81% of voters surveyed said they had a favorable view of Carson – that’s the highest ranking any candidate saw in the survey – and just 6% have an unfavorable view of him. Compare that to Trump’s 52% favorability rating, with 33% of voters reporting an unfavorable view of him.

“These results mark a significant shake-up in the leaderboard from Monmouth’s Iowa poll taken before the first debate,” Patrick Murray, director of the independent Monmouth University Polling Institute, said in a release. “Carson and, to a lesser extent, Fiorina have surged, while Walker has faded into the background.”

A Bloomberg/Des Moines Register of Iowa voters showed similar findings, with Carson earning 18% of voters, closing in on Trump who lead with 23%; when first and second choices were combined, the pair tied.