Donald Trump is still at the top of GOP primary polls, but recently there's been a surprising second-place finisher — Dr. Ben Carson.

Since the party's first debate on August 6, the retired pediatric neurosurgeon has surged past Jeb Bush and every other non-Trump candidate in national polls, in Iowa, and in New Hampshire. In some of these polls, he's been quite close behind Trump — and in one late August Iowa poll, he was tied with the billionaire for first.

Beyond that, Carson's favorability ratings among Republicans are sky-high, and one poll shows him as the only GOP candidate leading in a one-on-one matchup against Trump.

All this has come as a surprise to national commentators, who didn't find Carson too impressive in the first GOP debate. He was low-key, he didn't get to speak all that much, and when he did, his answers on policy weren't particularly impressive.

Carson's strengths: biography, positivity, outsider status, evangelical cred, and his message on race

But Carson has a great deal going for him. Like Trump, he's an outsider candidate who stands out from the career politicians in the field, and who condemns "political correctness."

Unlike Trump, though, he has a positive demeanor, a truly inspirational life story, credibility with the evangelical community, and seeming credibility on matters of race.

When Jenée Desmond-Harris interviewed some conservative white Ben Carson superfans in South Carolina in January, she found they were most enthusiastic about what she called the "made-for-Hollywood narrative arc of his life." Carson grew up poor in Detroit, but after working and studying hard, he became a successful and famous neurosurgeon.

"It goes to show that if you have a dream and fulfill that dream, it can be done," 71-year-old Martin Kolar of Myrtle Beach told her. Others praised Carson's faith and character — key selling points to evangelical voters, who preferred Carson to Trump in a recent poll of Iowa Republicans.

Sometimes, however, these citations of Carson's biography can have an implicit — or not so implicit — racial undertone. "He would be a wonderful role model for everyone, especially for the black people," 72-year-old Peggy Kemmerly of Elongee said. "You know, to get them off entitlements. He could open doors. Well, doors have been opened for them, but unfortunately they haven't accessed them." And Kolar said that he hoped Carson "removes the hyphen" in African-American to identify as "just American, to heal the racial divide we've been forced into."

The debate moment that helped Carson the most

Despite what seemed to have been an unmemorable debate performance, there was one exchange where Carson clearly struck a chord with the audience. It was his response to a question from Megyn Kelly about race relations, which was interrupted by loud and sustained applause:

You know, we have the purveyors of hatred who take every single incident between people of two races and try to make a race war out of it, and drive wedges into people. And this does not need to be done... I was asked by an NPR reporter once, why don’t I talk about race that often. I said it’s because I’m a neurosurgeon. And she thought that was a strange response. I said, you see, when I take someone to the operating room, I’m actually operating on the thing that makes them who they are. The skin doesn’t make them who they are. The hair doesn’t make them who they are. And it’s time for us to move beyond that [loud, heavy applause]. Because our strength as a nation comes in our unity. We are the United States of America, not the divided states. And those who want to divide us are trying to divide us, and we shouldn’t let them do it.

Though Carson was vague about just who those "purveyors of hatred" trying "to make a race war" might be, the implication was clear — they're liberals. Carson is saying that although he's black, he's enlightened enough not to focus on unimportant matters of race that "divide us," and will instead take a race-blind approach to unite Americans.

That's just what conservatives want to hear. As racial issues have gained salience in the age of Ferguson and Black Lives Matter, Republican responses have frequently seemed adrift and uncertain. So Carson — who is not just a black Republican but was, as Desmond-Harris put it, "a black folk hero" due to his rags-to-riches story — likely seems to many conservatives to be a very effective messenger pitching a conservative approach to racial issues.

Indeed, Carson has been a frequent critic of Black Lives Matter protesters, and wrote a recent op-ed telling them to focus less on police brutality and more on improving values, preventing drug use, and reducing dependence on government. He also mocked the offense some have taken at the use of the phrase "all lives matter" as "political correctness going amok." Instead, he said, "Of course all lives matter, and of course we should be very concerned about what’s going on, particularly in our inner cities."

Carson's major weakness, of course, is his lack of political experience. He's never run for office before, and the strains have showed this year, with his campaign experiencing turmoil and staff turnover. Despite all that, though, it's clear that — for now — Republican voters are paying close attention to what the doctor has to say.