The Rev. Al Sharpton said he could announce by this weekend whether he is endorsing Hillary Clinton or Sen. Bernie Sanders -- or neither of them -- for the Democratic presidential nomination.

Sharpton's vetting of the Democrats has attracted plenty of media attention -- to the candidates and to Sharpton himself. Less clear is how much impact an endorsement would actually have on the contest.

The plot lines are similar to those faced by the two top contenders in 2008. Then as now, Clinton was trying to hold onto a big lead among black voters, an important constituency in the Democratic electorate. And Barack Obama, like Sanders eight years later, was not well known to black voters, with whom he needed to make inroads if he was to win the nomination.

In the end, after Obama made the pilgrimage to Harlem to break bread with Sharpton, the veteran civil rights activist ended up not formally endorsing anyone. But he made it no secret that he was backing the Illinois senator over Clinton.

Last week, Sharpton met with Sanders at Sylvia’s restaurant. It was the same venue where he and Obama were photographed eating and chatting in 2008. Sharpton was among a group of leaders of civil rights groups, including the NAACP Legal Defense Fund, the Urban League and the Leadership Conference on Civil and Human Rights,  who met with the Vermont senator on Thursday in Washington. Clinton had a more low-key session with Sharpton, and she also met with the larger group of leaders earlier this week.

Late Thursday Sharpton said there has been too much focus on who and when he will endorse, and he would not make an announcement immediately. "I’m purposely not doing it today or tomorrow. I want the issues that we discussed to linger out there. I'm much more interested in the issues than the endorsement."

Sharpton said in an interview Thursday morning that the series of meetings were an important part of his decision-making process.

"What I've tried to project to the candidates is that we are concerned about criminal justice matters, from mass incarceration to mandatory sentencing to police reform. We’re concerned about voting rights, and we’re concerned about about economic disparities, independent of just income disparity because of the racial component," he said. "For me to make endorsement before the candidates have addressed the issues is to undercut what we’re about. I lead a civil rights organization, not a political organization."

The Sanders campaign, in a statement after the meeting, said the senator talked about issues such as voting rights and the importance of pushing back on Republican Senate leaders' threats to stall the confirmation of a nominee to replace Justice Antonin Scalia, who died Saturday. He also assured the group that he does not ignore the impact of race on economic issues. "I understand that the African-American community has been harder hit than any other community in America."

Looming over all of it is whether a Sharpton endorsement matters.

On Feb. 27, South Carolina will hold its Democratic primary, the first nominating contest in which black voters will play a significant role. African Americans are estimated to make up more than half of the Democratic electorate in the state.

Polls have shown Clinton holding a sizable lead among black voters in South Carolina, where she is looking to regain some of her front-runner swagger after barely winning in Iowa and losing to Sanders by 22 points in New Hampshire. Sanders has created some buzz among African Americans in South Carolina and Georgia, which holds its primary on March 1. A couple of state lawmakers in each state have switched their support from Clinton to Sanders, and young black voters, including many who align themselves with the Black Lives Matter movement, have rallied around Sanders.

Does Sharpton have the power to move the needle one way or the other for Clinton or Sanders?

"Nobody speaks for all blacks; nobody speaks for all of anybody," Sharpton said. "I don’t think anybody delivers voters, but some people have standing where people say, 'I want to hear their opinion because I'm usually agreeable with them or I know who they are.' I'm concerned about the issues; I'm not concerned about trying to show some political muscle."

Neither campaign responded to requests for comment about what benefits they hope to reap from a Sharpton endorsement. Both Clinton and Sanders have touted endorsements of black elected officials and celebrities. And because criminal justice has emerged as a top issue for many African Americans, the candidates also have sought the support of family members of unarmed black people who have died during encounters with law enforcement or white civilians claiming self-defense.

Sharpton’s organization, the National Action Network, is small compared to the legacy civil rights groups. He also hosts a talk show on MSNBC, although it was cut back from a daily to a weekly program airing on Sundays. His national profile also results from his tendency to become involved -- some would say self-servingly so -- in news stories related to racial injustice.

He might well have some older fans who appreciate his years of agitating, but among the new crop of young activists, Sharpton is considered part of the old guard. He and some Black Lives Matter activists have sparred in the media. During a 2014 rally in Washington to call for criminal justice reform, aides to Sharpton, who organized the event, tussled over a microphone with some activists from Ferguson, Mo., where the shooting of Michael Brown by a white police officer a few months earlier had magnified the Black Lives Matter movement.

Would a Sharpton endorsement turn off Sanders’s youthful supporters? Would it help the senator from Vermont pick up support with older African Americans, who are well aware of Clinton's baggage but still give credit to her husband, the former president, for presiding over a strong economy in the 1990s and seeming at home in a black Baptist church?

There's no evidence that endorsements matter much to voters. Nor is there evidence to indicate how much Sharpton’s support mattered in the last contested Democratic presidential primary.

By the time the reverend got around to publicly dropping hints that he was privately supporting Obama in 2008, the Illinois senator had not only caught up to Clinton in the polls, but he had decisively won the South Carolina primary. (In similar fashion, Sharpton, after being courted by the top candidates, declined to make a formal endorsement in the Democratic primary for New York mayor, although he was widely believed to have been behind the eventual winner, Bill de Blasio.)

The biggest beneficiary of Sharpton’s 2008 endorsement seems to have been Sharpton himself, who has been a frequent visitor to the White House during the past seven years and has managed to snare top Obama administration officials to speak at National Action Network events.

This story has been updated to reflect that aides to Rev. Al Sharpton clashed at a Washington rally in 2014.