Benita Stembridge was already a Hillary Clinton supporter before she heard her former senator deliver campaign remarks to a packed auditorium Tuesday in New York City. Stembridge, 65, who runs a job skills training nonprofit, doesn’t want Clinton to assume anything about why she has her support.

“I’m not a person that votes for someone because I like them,” said Stembridge, an African-American. “If they can’t come and be with us, why would we vote for someone like that?”

Scores of black community leaders around the nation, Stembridge included, often seek genuine kinship before supporting Democratic candidates. That’s especially true if they are white and somewhat unknown to the community, like Vermont Sen. Bernie Sanders, she said.

As Clinton and Sanders crisscross the country to shore up African-American votes, there’s no disputing that black voters swing solidly for Democratic candidates. But just how strong that support is can depend on geographic location — blacks who live in the South where whites are more likely to be conservative Republicans vote for Democrats by a much wider margins than in many areas of the North, according to recent voter data analysis. In contested races, not all Democratic candidates get a pass from black voters, who are listening for candidates to hit the right notes on issues of historical significance to the community, experts have said.

“The Democratic Party can’t rest on their laurels and assume that African-Americans are ready to keep rewarding them for decades-old civil rights victories,” said Andra Gillespie, associate professor of political science at Emory University in Atlanta. Voting rights for minorities are imperiled by state-level voter ID laws, law enforcement conduct in communities of color is under intense scrutiny and economic opportunity for blacks continues to lag behind whites, said Gillespie, naming some key issues.

“If you have a candidate that appears particularly tone deaf on those issues, they probably won’t do well with black voters,” she added.

Since launching their campaigns last year, Clinton and Sanders have been vying for primary election support among black voters. Both were in New York City days apart from each other to meet with the Rev. Al Sharpton and other black leaders. Clinton stopped in the historically black Harlem neighborhood Tuesday afternoon to address how, as president, she would break down achievement barriers for blacks.

“Race still plays a significant role in determining who gets ahead in America and who gets left behind,” Clinton told a packed room of dignitaries that included New York Gov. Andrew Cuomo, New York City Mayor Bill de Blasio and former Attorney General Eric Holder.

But Clinton and Sanders have also struggled with their credentials on criminal justice issues. First it was Sanders who last year was confronted by activists in the anti-police brutality movement Black Lives Matter, after saying that “all lives matter.” Then it was Clinton who, as of late, has had to distance herself from the mass incarceration and welfare reform policies that she and former President Bill Clinton supported when they were in the White House.

hillary bernie black voters Sen. Bernie Sanders of Vermont and former Secretary of State Hillary Clinton arrive on stage ahead at the start of the PBS “NewsHour” Democratic debate in Milwaukee, Feb. 11, 2016. Photo: Reuters/Darren Hauck  

Ahead of the South Carolina Democratic primary Feb. 27, which is considered the first opportunity for a representative population of African-Americans to weigh in on the election, Clinton appeared to have the black vote sowed up in the Palmetto State. The latest Public Policy Polling survey of voters ahead of primaries in South Carolina was conducted Sunday and Monday, with a margin of error of 3.3 percentage points.

Clinton holds a double-digit lead over Sanders, 55-34, according to a poll of 525 likely Democratic primary voters. But while Sanders has tied Clinton in support among white South Carolina voters, the former secretary of state has a strong lead among black voters — 63 percent said they back Clinton compared with 23 percent who back Sanders. But Sanders has made inroads with black South Carolinians, narrowing the 86-11 lead that Clinton had last November.

During presidential elections, African-American voters break for Democrats over Republicans by margins as high as 99-1 percent, compared with a 43-57 spread among white voters, according to Gallup polling. In 2012, President Barack Obama received 95 percent of black voter support over former Massachusetts Gov. Mitt Romney. These dynamics make courting black voters nonnegotiable for Democrats and a sometimes afterthought for Republicans, said Todd Shaw, associate professor of political science at the University of South Carolina in Columbia.

“The black vote does matter when it comes to the Democratic primary in this state,” Shaw said in a recent interview. “If you’re going to be a presidential contender with any chance of getting the delegates from this state, you have to get the African-American vote.”

Shaw said Democrats support of civil rights legislation that sought an end to racial discrimination and voter disenfranchisement among blacks in the U.S. South solidified black loyalty to the Democratic Party. The Civil Rights Act of 1964, proposed by President John F. Kennedy and signed by President Lyndon Johnson, both Democrats, allowed Johnson to carry 94 percent of the black vote against his Republican opponent Barry Goldwater that year, according to researchers at the Joint Center for Political and Economic Studies in Washington, D.C.

Voters in majority-minority geographic areas also tend to break for Democrats, especially when African-Americans make up a clear majority. This is easier to spot in southern regions, but also exists in the North, said Gillespie, the Emory University professor. 

Gillespie’s analysis of 2014 midterm election voter data found that black voters were a critical component of the electorate in U.S. Senate races, including those in Colorado, Kentucky, Michigan and North Carolina. The black vote was also important in gubernatorial contests in Georgia, Illinois, Florida and Wisconsin. The dynamic was based on enthusiasm for the candidates, regardless of party affiliation, and their ability to cast a vote free of suppressive tactics such as strict voter ID law.

Voting rights issues are paramount for Lonnie Randolph, president of the NAACP’s statewide organization in South Carolina, who hosts a weekly civil rights radio program. At 65, Randolph remembers being 15 year olds when Johnson signed the Voting Rights Act of 1965. He often tells listeners that his father had never been able to vote without risking his life and died the morning the act was signed.

“There has never been an occasion when I’ve gone on the air and not spoke about voting,” Randolph said in a recent phone interview. “South Carolina cannot be overlooked” as a bellwether for the black vote, he added.

There’s long been a debate about whether prominent national leaders have influence in black communities around the country. That both Clinton and Sanders sought meetings with Sharpton, the civil rights activist, and members of the Black Lives Matter movement speaks to the perceived value of their opinion among African-Americans, experts have said.

Sharpton, a liberal Democrat who has said he would not endorse a candidate on behalf of his Harlem-based National Action Network (NAN), would still find a kind ear as an advocate among black voters during an election, said the Rev. Nelson Rivers III, NAN’s national vice president for religious affairs and external relations. “He carries more sway than anybody on the Republican side,” Rivers said. “They would be more attuned to him than [South Carolina Gov.] Nikki Haley or [U.S. Sen.] Tim Scott," he added, referring to conservative politicians who are nonwhites.

Blacks don’t think or vote as a monolith, despite data suggesting they do, experts have said. But many do fall back on the familiarity of the candidate asking for their vote, Stembridge said at the Clinton event Tuesday.

“Politicians can come and promise a lot of things,” she said. “But you can’t buy respect. There has to be a lot of it. You’ve got to give us something to draw us in.”