The African-American vote has always been important for Hillary Clinton, but as her lead narrows in the race for the Democratic presidential nomination, support from that crucial demographic is more essential than ever.  A new, key endorsement from former Attorney General Eric Holder may be exactly what she needs.

As the nation’s first black attorney general, Holder maintains a special place in the hearts of many African-Americans, not only because of his association with President Barack Obama, but also for the civil rights causes he championed as head of the Justice Department. Clinton and rival candidate Vermont Sen. Bernie Sanders are competing for support from a voting bloc that some have accused Democrats of taking for granted. But political experts say the power of Holder’s endorsement could help the former secretary of state cement her status as the preferred candidate among black voters.

“It’s a very key endorsement for Secretary Clinton. He was the most visible black cabinet member of Obama’s administration,” said Steven Taylor, a professor of government at American University in Washington, D.C., who focuses on the politics of race and ethnicity. “Even though Obama hasn’t made an endorsement, the public will see this as a proxy endorsement.”

EricHolder Former U.S. Attorney General Eric Holder endorsed Hillary Clinton for president Wednesday. Above, Holder speaks at the Securing Sport 2015 conference, Nov. 5, 2015. Photo: Eduardo Munoz for ICSS

Minority voters, and particularly African-Americans, are a crucial voting bloc in the Democratic primaries. After the primarily white Democratic electorate in Iowa and New Hampshire, the next primaries fall in states like Nevada and South Carolina, where voters are much more diverse. In recent days, Sanders has pulled even with or ahead of Clinton in both New Hampshire and Iowa, and he has shrunk her lead nationally, making the more diverse primary contests even more important for the former secretary of state.

Holder will campaign for Clinton in a visit to South Carolina, the Associated Press reported Wednesday, attending both a state Democratic Party dinner with her Saturday and a debate Sunday sponsored by NBC News and the Congressional Black Caucus.

South Carolina, where African-Americans make up a significant portion of Democratic primary voters, has become a special focus for Clinton. Polling has consistently shown her as many as 71 points ahead with black voters in the state.

And this support isn’t new. In 2008, when Clinton ran against Obama for the Democratic nomination, she initially held the lead among black voters, before several missteps on her part and Obama’s historic campaign won him the overwhelming majority of African-American support. One of the most notable gaffes came when Clinton’s husband, former President Bill Clinton, was said to have insinuated that Obama was doing well in South Carolina due only to his race.

Without Obama in the running, many have assumed that Clinton will have the black vote wrapped up in 2016. But there is lingering skepticism over her establishment politics and what some voters have seen as a tendency to pander to African-Americans or take their support for granted.

“A lot of black voters haven’t forgotten the missteps Clinton had with black voters and Barack Obama in 2008. There’s not the same level of support for her as there was for Obama,” said Leah Wright Rigueur, a professor at Harvard University’s Kennedy School of Government in Cambridge, Massachusetts, who focuses on race and politics. “So what Hillary Clinton needs to do is not only ensure African-American voters come out for her, but for them to come out in the same record numbers that they did for Barack Obama. Eric Holder supporting her is the first step toward that.”

Because attorney general is not an elected position, there is little official polling of public opinion about Holder’s time as the nation’s top prosecutor, but a look at African-American media shows his popularity. Holder was frequently profiled by magazines such as Essence and Ebony during his five years as attorney general, and he was named to Ebony’s Power 100 list of influential African-Americans in 2012. The Root called him a “black political superhero” last year when looking back on his work in Obama’s cabinet.

Some have criticized Holder for failing to close the Guantanamo Bay detention camp, but Rigueur said most voters will think of the former attorney general as “Obama’s attack dog on civil rights and civil liberties.” He received significant attention, for example, for the blistering Department of Justice report on Ferguson, Missouri, which found that the city’s officials and police department often engaged in racially biased practices.

His credibility in areas like criminal justice is likely to help Clinton connect with voters on an authentic level, political analysts said. This is an area where she routinely struggled, particularly in comparison to Sanders. While Clinton has been criticized as pandering for changing her campaign logo to honor Rosa Parks and celebrate Kwanzaa, Sanders has been campaigning with the rapper Killer Mike, who has talked about substantive reasons he supports the Vermont senator, including the candidate's stance on the Voting Rights Act, healthcare, education and ending the war on drugs.

“The people who Barack Obama was able to reach who the Democratic Party needs are black men between the ages of 18 to 35, many of whom had not voted before or were not excited about the political process,” Rigueur said.

To reach these voters, Rigueur said, Clinton will need to up her ground game and reach out to voters on a personal level. Another area where Clinton will likely need support is from African-American women, who Rigueur said are the Democratic Party’s most consistent and reliable voting bloc. She has seen many women turn out at African-Americans for Hillary events already, and expects the campaign to court more women as election season continues.

An endorsement from a prominent African-American like Holder can go a long way toward helping the ground game, said Taylor, the American University professor.

“Nothing works more than having a sign posted in front of somebody’s house because that tells people somebody they know is endorsing this person,” he said, comparing Holder’s endorsement to political yard signs. “That really makes a lot of people think to come to the polls. It’s somebody very close to them, so the closer you get to a grassroots endorsement the better.”