The retired Johns Hopkins neurosurgeon and former Marylander, who struggled to gain attention at the first GOP debate, has surged in recent weeks to second place in the polls — and appears to be the only candidate posing a threat to billionaire front-runner Donald Trump.
Carson, who turns 64 on Friday, will take the debate stage as his candidacy is hitting its stride. His soft-spoken, understated delivery has offered a contrast to Trump's bellicosity, while his background allows him to maintain credibility with voters who want a political outsider.
"Folks are looking for someone who is more calm and deliberative rather than boisterous and belligerent," said Douglas Gross, a former aide to Iowa Gov. Terry Branstad. "At the same time he's also new and fresh."
With four and a half months to go before the Iowa caucus, polls show Carson rising from the middle of a crowded field of candidates to second place nationally. A CBS News/New York Times poll released Tuesday put Carson within four points of Trump, who has led the pack all summer.
Carson has also gained ground in Iowa, the nation's first presidential nominating state, and has been polling in double digits there since mid-August. Gross and other observers said the increase is reflected on the ground in Iowa, where Carson has gained volunteers and organization.
Eleven GOP candidates will appear at the Ronald Reagan Presidential Library in California for a debate that will be broadcast by CNN. Because of his standing in the polls, Carson will be positioned next to Trump on stage.
Former Florida Gov. Jeb Bush, Wisconsin Gov. Scott Walker, Carly Fiorina, Ohio Gov. John Kasich, New Jersey Gov. Chris Christie, Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, former Arkansas Gov. Mike Huckabee and Kentucky Sen. Rand Paul also made the cut for the main debate.
During the first debate last month, Carson took an early question, but wasn't called on again for about 30 minutes.
"I wasn't sure I was going to get to talk again," he joked at the time.
But now Carson can expect to get far more airtime — and, as one of the few candidates who has neither run for nor held public office, will likely face questions testing his ability to run a presidential administration.
How he uses that opportunity, observers said, will offer insight into the sustainability of his momentum.
Whether he can maintain his standing is an important question; candidates with early leads are prone to faltering. At this point in the last election cycle, former Texas Gov. Rick Perry was leading polls for the Republican nomination. But he stumbled on the debate stage, finished fifth in Iowa and dropped out of the race.
Louis Pope, a Republican national committeeman from Maryland, called Carson "a breath of fresh air for some people who are used to listening to political-speak."
"There's just a lot of frustration with traditional politicians, and voters want to see something different."
But Pope said that will likely change with time.
"I don't think this will last forever," he said.
Carson — a former Baltimore County resident who now lives in Florida — has recently avoided the statements on social issues that forced past apologies. He gained attention —- and financial support — early on for comparing the United States to Nazi Germany, describing Obama's health care law as the worst thing that has happened to the nation since slavery, and likening homosexuality to bestiality.
But while Carson has grown more disciplined, he hasn't avoided controversy entirely. At a campaign event in California this month he questioned Trump's faith.
"I realize where my successes come from, and I don't in any way deny my faith in God," said Carson, a Seventh-day Adventist. "And I think that probably is the big differentiator. ... That's a very big part of who I am — humility and fear of the Lord. I don't get that impression with him."
The comment drew a quick rebuke from Trump.
"Who is he to question my faith?" the front-runner asked. "He doesn't even know me."
Carson called a truce, and apologized.
The spat comes in the context of the broader GOP fight for evangelicals — a key voting bloc in Iowa. Both Carson and Trump are doing well with that group, but Carson invokes religion and religious themes more often. It was, after all, at the 2013 National Prayer Breakfast in Washington at which Carson became a favorite of Tea Party conservatives by openly criticizing nearby President Barack Obama.
"The evangelical voters are a massive block in the Iowa caucus and they often look for candidates who speak their values and speak like them," said Christopher Budzisz, director of the Loras College Poll. "Trump is doing well with evangelicals — especially for a candidate who isn't traditionally from that group — but Carson is clearly attractive."
Carson is also appealing to voters who don't want to back an elected official, and his personal story has always been among the most compelling in the field. Born into poverty in Detroit, Carson graduated from Yale and the University of Michigan's medical school, and then led the pediatric neurosurgery department at Hopkins.
He won international acclaim in 1987 when he became the first surgeon to successfully separate twins conjoined at the head. On the campaign trail, he frequently recounts miraculous surgeries to underscore the importance of faith.
Aides to Carson did not respond to interview requests from The Baltimore Sun.
As his influence grows nationally, Carson has remained popular in Maryland, though the state's April 26 primary is likely to foreclose GOP voters from having much influence in picking the nominee. Carson won a straw poll released Tuesday by the Maryland Republican Party, besting Trump by nearly 6 points.
CNN will broadcast the main GOP presidential debate at 8 p.m. Wednesday. Another debate, featuring candidates with lower poll numbers, will air at 6 p.m.