As Mayor Bill de Blasio stands at the precipice of launching a bid for the 2020 Democratic presidential nomination, voters who have long been central to his base here in New York City are expressing skepticism about his recent wanderlust, and frustration about what it may mean for his handling of issues at home.

Voters overwhelmingly say de Blasio should not run for president—and experts say if he does enter an already crowded and historically diverse field of declared Democratic candidates, he’ll need a different playbook than what worked in his 2013 run for mayor.

The mayor’s base was built in Brooklyn, where voters repeatedly turned out for him in races for City Council, Public Advocate and Mayor. His highest approval ratings come from black voters, whose support for him continues to outpace every other group by double digit margins.

Speaking at the National Action Network’s Conference last week, de Blasio urged the largely black audience to keep demanding more from the country’s leaders, offering a sentiment that might reflect what he tells himself.

“Don't let anyone tell you what you can't do. Don't let anyone talk you out of your own power,” he said gripping the podium. The ballroom was packed, shoulder-to-shoulder, but even the mayor’s biggest applause lines were met with a tepid reception. People were eagerly awaiting the next speaker: Stacey Abrams, who almost became the nation’s first black woman governor in a contentious election in Georgia marred by voting irregularities.

When de Blasio was propelled by black voters from unlikeliest candidate to mayor in 2013, he did so by addressing New Yorkers who felt ignored for more than a decade under the previous administration, according to Christina Greer, an associate professor of political science at Fordham University and a scholar of black studies. She said she was “quite excited,” about the prospect of a new era.

That excitement turned to disappointment over de Blasio’s squabbles with the press and what she perceives as disinterest in his second term. She also stressed that he can't frame himself the same way he did when he first ran for mayor.

“Let's be honest: 2013 was a very different racial moment,” Greer said.

Greer referenced the Dante ad, a campaign commercial that featured de Blasio's teenage son, a young black man with a full afro making the case for his father. The ad was considered widely successful, serving as a reveal to some and a reminder to others of his biracial family.

This was before the death of Michael Brown in Ferguson, Eric Garner in Staten Island, the rise of a national Black Lives Matter movement and a shift in the conversation about justice, representation and how policy debates are shaped by experience and identity.

“I don't know if you pull that kind of ad today if it would be received the same way in this politicized, racialized moment,” said Greer.

De Blasio's supporters dismiss these critiques. Peter Ragone, a longtime friend and former City Hall adviser, said the mayor has been among the vanguard of talking about issues of race, justice and economic inequality.

“There's a simple fact that Bill de Blasio has never been the darling of elite opinion makers and the media,” Ragone said, arguing that de Blasio has spent years cultivating relationships with voters that aren’t reflected in the stories that make the cover of the city’s tabloids. Those relationships, Ragone said, are built on de Blasio’s personal understanding of the lives of everyday New Yorkers.

“He doesn't come from a position of power, he doesn't come from a position of privilege. He understands that what their struggles are,” said Ragone. “And that relationship with voters has been unshakeable through three elections in New York City.”

Back at the National Action Network Conference, Marian Johnson from Jamaica Hills, Queens said she voted for the mayor in the past, but she’s not so sure he will earn her vote again. She expressed frustration with de Blasio’s recent travels. In recent weeks, he’s visited early battleground states such as Iowa, New Hampshire, South Carolina and Nevada. Johnson wondered what he was doing to fix the city's public housing authority.

“You the mayor,” said Johnson. “You came into the city when NYCHA was crumbling and now it’s still crumbling and you running around the country.”

Patricia Vestral from the Bronx, a big de Blasio supporter in 2013, said the candidate she was most excited by so far was Julian Castro, the former Housing and Urban Development Secretary and one-time mayor of San Antonio. Asked about de Blasio’s possible bid for higher office, she raised her eyebrows.

“Hmmmm,” said Vestral thinking aloud then adding, “can I put a hold on that one?” she said

Similar skepticism was borne out back in his Park Slope stomping grounds. Outside the YMCA, a place de Blasio frequents for his daily workout despite the drive from Gracie Mansion, Onilaja Waters pointed to problems with the city’s transit system.

She also pointed to the city’s highly segregated schools.

"Black children and people of color are still not getting a proper education," Waters said. "I would tell the people of the United States that this is someone who talks a progressive agenda, but what we see in New York City is very mixed."

For more, listen to reporter Brigid Bergin's segment for WNYC:

Brigid Bergin is the City Hall and politics reporter for WNYC. You can follow her on Twitter at @brigidbergin.