He has a rags-to-riches personal story, no political experience and controversial views on social issues. Ben Carson, an African-American neurosurgeon, is rallying white evangelicals and now leads Trump in the polls.
Ben Carson was the first, and so far the only, presidential candidate to visit Ferguson. The suburb of St. Louis, Missouri, erupted in protests and riots last year after an unarmed black teenager, Michael Brown, was shot dead by a white police officer, Darren Wilson.
Ferguson has triggered a renewed debate about race relations, the criminal justice system and civil rights in America. The Republican presidential debates have all but ignored the issue. Carson himself has accused the GOP of neglecting African-American voters.
Carson knows something about racial and economic inequality in America. He grew up in poverty, raised by his mother, a single parent, in Detroit's violent inner city. His two older cousins were killed in the streets. He didn't believe he would live past his 25th birthday.
Pushed by his mother, who was illiterate, to read and value education, Carson went on to become a renowned neurosurgeon at Johns Hopkins Hospital in Baltimore. In 1987, he led a medical team that performed the first successful separation of Siamese twins conjoined at the back of the head.
During his September visit to Ferguson, Carson criticized law enforcement, saying the police had disrespected the community by leaving Brown's dead body in the street for hours. But he also said the black community in Ferguson was "unwilling to face the fact that Michael Brown was a bad actor." Carson has accused the Black Lives Matter movement of "bullying" political candidates.
In the past two presidential elections, the Republican candidates won single digit support from black voters. Carson hopes to change that. But according to Angie Maxwell, a professor of political science at the University of Arkansas, Barack Obama's presidency and racially charged events like Ferguson have solidified the African-American community's overwhelming support for Democrats.
Carson first joined the Republican Party in 2014, having previously been registered as an independent. He has never held political office and champions his lack of experience.
"I am not a politician, I don't want to be a politician," Carson said when he announced his candidacy for the Republican nomination in May. "Politicians do what's politically expedient, and I want to do what's right."
Like Trump, Carson's status as a political outsider has won him the support of Republican primary voters who are fed up with traditional candidates, according to Maxwell. While the media has focused most its attention on Trump, Carson has quietly become a frontrunner in the Republican field.
He leads Trump by four percent nationally in a New York Times/CBS survey published on Tuesday. In Iowa, an important early voting state, the neurosurgeon is ahead of the real estate mogul by 14 percent, according to a Monmouth University poll. A Seventh Day Adventist Christian, Carson is mobilizing white evangelicals, one of the Republican Party's core constituencies.
"He's playing the evangelical card much better than Trump does," Maxwell said. "Religion is probably the single greatest motivator within the GOP. Without a true evangelical in the race, Ben Carson is getting those people."
His grassroots campaign has also edged out the other candidates in fundraising. Carson brought in $20 million during the third quarter, nearly double Jeb Bush, the son and brother of two past presidents.
According to the Washington Post, 60 percent of the contributions to Carson's campaign were less than $200. More than 400,000 people made a total of 700,000 donations, the Post reported, citing Carson's campaign.
The neurosurgeon came to political prominence in 2013 when he spoke at the National Prayer Breakfast, a Christian event held annually in Washington and attended by the president. Sitting feet away from President Barack Obama, Carson criticized his signature health care reform law. Virtually overnight, the neurosurgeon became a conservative media darling.
During that same 2013 speech, Carson also criticized political correctness, calling it "dangerous" and a "horrible thing." It's a theme he's taken to the campaign trail. The presidential candidate has made controversial comments about homosexuals and Muslims.
Asked on NBC's Meet the Press in September if Islam is consistent wit the US constitution, Carson said that he "would not advocate that we put a Muslim in charge of this nation."
In a 2013 Fox News interview, Carson explained his opposition to same-sex marriage. He said "no group - be they gays, be they NAMBLA, be they people who believe in bestiality, it doesn't matter what they are - they don't get to change the definition." NAMBLA, which stands for the North American Man/Boy Love Association, represents pedophiles.
In an interview with CNN last March, Carson argued that being gay is a choice: "A lot of people who go into prison, go in straight and when they come out, they're gay," he said.
In a 2006 debate with scientist and atheist Richard Dawkins, Carson said he doesn't believe in evolution. The neurosurgeon and devout evangelical once said that Darwin's theory of evolution was "encouraged by the adversary." He has also dismissed the Big Bang theory as a "fairy tale."