He’s not on the ballot, something he’s repeatedly noted, since winning re-election in 2012. Yet President Barack Obama is pushing one of his key constituencies — African-American voters — to the polls for Hillary Clinton, who can’t win without their overwhelming support.

[READ: Donald Trump’s Dismal Appeal to Black Voters]

“If you don’t vote, that’s a vote for [Republican nominee Donald] Trump. If you vote for a third-party candidate who’s got no chance to win, that’s a vote for Trump,” Obama said during an interview on “The Steve Harvey Morning Show” broadcast last week. And the stakes, he argued, are high — maybe even historic.

“So the notion somehow that, ‘Well, you know, I’m not as inspired because Barack and [first lady] Michelle [Obama], they’re not on the ballot this time, and, you know, maybe we kinda take it easy’ — my legacy’s on the ballot,” the president said. “You know, all the work we’ve done over the last eight years is on the ballot.”

However, getting black voters to embrace Clinton — Obama’s former rival-turned-anointed successor and first lady to former President Bill Clinton, once admiringly called “the first black president” until the real thing came along — is easier said than done.

Despite her credentials, including a history of fighting for African-American issues, tenure in Obama’s cabinet and having two black women as inner-circle advisers, a recent New York Times report found a clear lack of enthusiasm for Clinton among many young African-American voters. The report also found that, compared with Obama, she’s underperforming with black men in key swing states, including Florida and Ohio.

And former Virginia Gov. Doug Wilder, the nation’s first black governor since Reconstruction and one of Democratic vice-presidential nominee Tim Kaine’s predecessors in the Old Dominion’s governor’s mansion, says Clinton doesn’t have a coherent message that would fire up black America.

“For her to go out and say to the African-American community, ‘I want you to elect me so that we can continue the legacy of Barack Obama,’ what exactly is it that you want to continue?” Wilder told the Washington Post last week.

There’s no doubt Clinton’s got the black vote on lockdown; it’s a highly loyal Democratic constituency that’s largely given the side-eye to Trump, a political novice who has veered from ham-fisted “black outreach” to describing African-American communities as dystopian hellholes of bad schools, substandard housing and random deadly violence.

But such talk has made the celebrity billionaire a sensation with the white working class in key Rust Belt states. His unorthodox, populist campaign, coupled with restless swing voters eager for change, has managed to erase Clinton’s double-digit leads in national polls.

To soundly defeat Trump in November, analysts agree, Clinton needs the African-American vote to surge to the polls in record numbers like they did for Obama. Though the share of the national black electorate is roughly 12 percent, black turnout pushed past 13 percent in both 2008 and 2012, overrepresentation that helped Obama make history.

While exit polls showed overall voter turnout was down in 2012 compared to 2008, states where African Americans make up 20 percent or more of the population — including the Black Belt, the arc of Southern states sweeping from Louisiana to Maryland — saw a smaller turnout decline than the national average, with Georgia the only exception.

According to polls, however, the big love Obama got from black voters in 2008, and the buoyancy they gave him when he ran for reelection in 2012, hasn’t yet transferred to Clinton, says Kerry Haynie, a Duke University professor of political science and African-American studies.

“I’ve traveled around Durham [North Carolina]. I did not see one campaign sign in my barbershop — not even anything about the Clinton campaign,” says Haynie, who works in North Carolina, a key electoral battleground. Compared to 2008 and 2012, when Obama signs dominated the black community, Clinton’s presence there is so light “you wouldn’t even know there was an election.”

[RELATED: For Hillary Clinton, the African-American Vote Is Key]

Instead of backing Clinton, voters in North Carolina are more focused on defeating Trump. And Haynie says that can make a difference when ballots are cast.

“They aren’t talking about it with enthusiasm for Clinton but in opposition to Donald Trump,” Haynie says. “If you’re the candidate, you want people to be enthusiastic about you because it might affect turnout.”

To gin up excitement, the Clinton campaign says it’s been reaching out to black voters, from historically black colleges to barber shops and beauty salons to the Black Twitterati. They say powerful African-American surrogates like the Obamas have only begun to vouch for her. And they insist a low-key but intense voter-outreach campaign will yield big dividends at the polls.

“You’ll see the results of our efforts” in about 30 days, says Addisu Demissie, Clinton’s national voter outreach and mobilization director. “I’m confident that black people in this country are going to understand the stakes and are not going to let us turn back now.”

Yet the biggest factor working against Clinton could be Obama himself.

Having smashed a seemingly impenetrable racial barrier to serve two terms as leader of the free world, the nation’s first black president is legendary in the black community, with civil rights icon Martin Luther King Jr. as perhaps his only peer.

Clinton, by contrast, has acknowledged that, when it comes to campaigning, she’s less showhorse and more workhorse, with the nicks and scars that accompany three decades on the national stage. Under the best of circumstances, it’s a tough ask for black voters who cherish Obama — a thrilling, once-in-a-lifetime political phenomenon — to get as excited about her.

“Familiarity breeds contempt — that’s a good way of saying it,” Haynie says.

And though Clinton points to the work she did as a child-welfare advocate in Mississippi after finishing law school in the 1970s, and as Arkansas’ first lady when her husband was governor, her African-American critics haven’t forgotten her battle with Obama for the 2008 Democratic presidential nomination.

The epic, historic clash between a white woman and a black man for a major political prize tap-danced on the edge of race, including allegations the Clinton campaign fomented rumors that Obama was a drug dealer, and President Clinton’s acid-tongued critique that Obama’s success against his wife was, among other things, based on a “fairy tale.”

Back then, Clinton herself attacked Obama for his affiliation with the Rev. Jeremiah Wright, whose incendiary sermons condemned the U.S. for its racist past. She also walked past an opportunity to decisively shut down a whisper campaign that Obama was a secret Muslim, and once referred to herself as the candidate of “hard-working Americans, white Americans.”

Then there’s the 1994 Crime Bill, which President Clinton signed into law — and which some analysts say helped fuel the boom in the African-American incarceration rate. The bill, and Hillary Clinton’s vocal support for it as first lady, is a major bone of contention between her and young Black Lives Matter activists, an influential coalition whose agenda includes criminal justice reform.

Given Clinton’s record of fighting against childhood poverty and for public-school reform, “It’s sort of an unfair tarnishing of her,” Haynie says. “But all politicians do that — they make mistakes, they do things that they regret. If you look at the totality of public life, they do not [represent] who she was, who she is or what she represents.”

Nevertheless, it doesn’t negate the fact that Clinton “still has a race problem,” Melissa Harris-Perry, a political scientist at Wake Forest University and Elle editor-at-large, wrote in the magazine’s latest issue. “Like many of the challenges facing her candidacy, it is only marginally of her own making, but it is a problem nonetheless.”

Outreach aside, Harris-Perry wrote, Trump is exploiting the handicap in hopes of depressing black voter turnout. During their first presidential debate, Trump resurrected the 2008 campaign (“You treated him with terrible disrespect,” he told Clinton) and pushed the widely held view that Democrats, Obama included, take the black vote for granted.

“The African-American community has been let down by our politicians,” Trump said. “They talk good around election time, like right now, and after the election, they said, ‘See ya later, I’ll see you in four years.'”

That see-you-when-I-need-you shade, coupled with President Clinton’s anti-crime crackdown during the ’90s — at the urging of black politicians who represented crime-ravaged districts — are significant elements in the ennui towards Hillary Clinton.

“This summer’s #GirlIGuessImWithHer viral hashtag captured black voter ambivalence towards Clinton’s candidacy,” Harris-Perry wrote. “When Trump speaks of hellish inner city neighborhoods that need his special brand of law and order, he is tapping into an argument trumpeted for nearly two decades by former President Clinton, who claimed to have brought down crime by putting 100,000 officers on city streets.”

Demissie, the campaign’s voter outreach director, says Clinton has been working overtime to emphasize her connections to black America: she’s toured historically-black colleges and universities; she’s spoken at conclaves for the NAACP, the Urban League and National Association of Black Journalists, among others; and she’s engaging online with members of Black Twitter, including the Black Girl Magic coalition.

“You look at 40 years of [Clinton’s] career, and that’s what she should be judged upon,” Demissie says. “But that’s what campaigns are for. It’s our job to put a message out. That’s what we’re doing, as aggressively as we can. And that ramp is about to get real steep. Voters are going to tune in and hear our message loud and clear over the last 30 days.”

Though Obama’s central argument for Clinton to black voters is protection of his legacy, “the election can’t be just about the last eight years,” Demissie says. “Black voters understand the stakes here, especially given our opponent. I think the future of black families is on the ballot. I do think that’s a motivating argument.”

Democratic pollster Celinda Lake agrees. Obama’s success in 2008 and 2012 may have set a high bar with black voters — “It would be very difficult to replicate that again,” Lake says — but the president’s endorsement of Clinton, her work shoring up the black vote, and his calls to protect his historic legacy, should help her clear it.

[PHOTOS: The Big Picture — September 2016]

“If anything, African-American voters delivered the primary for her” against Vermont Sen. Bernie Sanders, her rival for the Democratic presidential nomination, Lake says.

“Hillary Clinton has the same level of engagement and strength among African-American voters as Democrats have traditionally had, other than Barack Obama,” says Lake. At the same time, she says, focus groups Lake has convened show black voters agree with Clinton and Obama that Trump is an existential threat; their positive response to Obama’s warning that his legacy is on the ballot “was off the charts.”

And Michelle Obama, her not-so-secret weapon, will help Clinton make inroads with African-American millennials in places like Georgia — a deep-red Black Belt state that nevertheless is in play, with the former secretary of state trailing by just five points. At the same time, Lake says, black support for Trump, which had recently bumped into the low single digits, has flatlined to around zero percent, and “nobody ever gets to zero in a poll” unless they’re trying.

Demissie says Clinton’s effort to reach black voters, combined with Trump’s near-deliberate alienation of them, should help catapult her into office in November, just as they did with Obama in 2008 and 2012.

“Reality is setting in. The choice is between two diametrically opposite candidates,” Demissie says “You have a candidate who has fought for black families her entire life, and someone who would take us far, far backwards.”

“I think that’s going to trump — pun intended — anything else that may be out there,” he said.

For Clinton to win the oval office, it will have to.

More from U.S. News

For Hillary Clinton, the African-American Vote Is Key

Donald Trump’s Dismal Appeal to Black Voters

Black Lives Matter Movement and the Bad News about Good Census Numbers

Can Barack Obama Help Hillary Clinton Win the Black Vote? originally appeared on usnews.com