The Associated Press

FORT LAUDERDALE, Fla.

Ayauna King-Baker loved Ben Carson’s “Gifted Hands” memoir so much that she made her daughter, Shaliya, read it.

So when Dr. Carson showed up in town to sign copies of his new book, Mrs. King-Baker dragged the giggly 13-year-old along to the bookstore so they could both meet him.

To Mrs. King-Baker, Dr. Carson’s “up-by-your bootstraps” life story makes him a genuine celebrity worth emulating in the African-American community. But she’s also a Pompano Beach, Fla., Democrat watching Dr. Carson’s performance in the Republican presidential polls.

For Mrs. King-Baker and many other African-Americans, the vast majority of whom are Democrats, there are two Carsons: One is a genius doctor and inspirational speaker and writer who talks of limitless horizons; the other is a White House candidate who pushes conservative politics and wishes to “de-emphasize race.”

How they reconcile the two may help determine whether Republicans can dent the solid support Democrats have enjoyed in the black community for decades.

President Obama won 95 percent of the black vote in 2008 and 93 percent in 2012. Dr. Carson wasn’t immune to the excitement of seeing the United States elect its first black president.

“I don’t think there were any black people in the country that weren’t thrilled that that happened — including me,” Dr. Carson told The Associated Press in a recent interview when asked about President Obama’s first victory. “Everyone had hope this would be something different. It was nice having that hope for a little while.”

Dr. Carson has since become an aggressive critic of the president. Dr. Carson rose to prominence in the Tea Party movement after repudiating the president’s health care law in front of President Obama during the 2013 National Prayer Breakfast. Today, Dr. Carson charges that the president’s performance has actually set black candidates back.

“I don’t think he’s made my path any easier,” Dr. Carson said. “So many people said there’d never be another black president for 100 years after this.”

Dr. Carson has not gone out of his way to court black voters this year. He insists he won’t change his message to attract specific audiences, although his campaign tried a rap-filled ad in early November.

He already has one convert — Mrs. King-Baker. She says she plans to change her registration to vote for the doctor in the Florida primary. “He has the momentum, he has the conversation, he’s very serious, he’s speaking to the people, and I just think he would be a very good president,” she said.

None of this will matter unless Dr. Carson survives the primaries, where he had been leading in early preference polls.

Black votes aren’t a major factor in GOP primaries. Only about 16 percent of African-American voters affiliated with the Republican Party in 2012. But they will be a factor in the November general election.

African-American voters are one of the few growing segments of the voting public. The percentage of black voters eclipsed the percentage of white voters for the first time in 2012, when 66 percent of blacks voted, compared with 64 percent of non-Hispanics whites and about 48 percent of Hispanics and Asians.

Carole Bell, a professor of communication studies at Northeastern University, estimates that Dr. Carson could attract as much as 25 percent of the African-American vote if he’s the GOP candidate. “That would be a tremendous accomplishment for the GOP at this stage,” she said.

Dr. Carson is better known by African-American voters than other black Republicans who ran for president, such as businessman Herman Cain, who achieved passing prominence in the 2012 race, and former Ambassador Alan Keyes before him.

Dr. Carson was a celebrated figure before he entered politics because of his work as a neurosurgeon. He led a team that successfully separated conjoined twins, which led to movie appearances, best-selling books, a television biography and a motivational speaking career that crossed racial lines.

“Black people were proud that Dr. Carson had become a famous surgeon and had accomplished what no one else ever had in separating the twins,” said Fredrick Harris, director of the Institute for Research in African-American Studies at Columbia University.

That’s part of his appeal, said Rebecca Britt, 43, a registered Democrat who also went to see Dr. Carson in Fort Lauderdale and buy his most recent book. “He’s one of the heroes in our community, with what he’s been able to accomplish in the medical field,” she said.

But can that translate into many black votes?

Dr. Carson has said he would not support a Muslim for president, a position his campaign says helped him raise money and attract conservative support. He has been critical of the Black Lives Matter movement, which drew its name from protests that followed the death of unarmed 18-year-old Michael Brown in Ferguson, Mo.

The retired neurosurgeon told the AP that Americans should take the focus off of race during a recent trip to Mr. Brown’s hometown.

Dr. Carson may draw support from conservative African-Americans and those already in the GOP, but it’s unlikely that he would make major inroads in the Democratic Party’s dominance among black voters in a general election, said D’Andra Orey, a political science professor at Jackson State University in Mississippi.

Given the GOP’s fraught history with African-Americans, it could be “nearly impossible for blacks to support a Republican who espouses what they deem to be racially conservative rhetoric,” Ms. Orey said. “Put short, it’s an uphill battle for any Republican who seeks out the black vote.”

Ms. Bell, the Northeastern professor, said Dr. Carson’s celebrity may have helped him at the beginning of his candidacy, but that shine may have worn off.

“He had tremendous positives before he started speaking as a potential candidate,” Ms. Bell said. “But the more he speaks, the more there are opportunities to sort of really show there’s a gulf between him and a lot of African-Americans.”