New York Mayor Bill de Blasio has ambitions to be a leading national voice for the progressive wing of the Democratic Party, but he faces a big challenge: getting voters around the country who barely know who he is to listen.

In his second year in office, de Blasio has invested more time in elevating his profile beyond the five boroughs with an eye toward influencing the 2016 presidential race.

This month alone, he hosted a Gracie Mansion gathering of progressive politicians and activists from across the nation, embarked on a Midwest speaking tour on income inequality and, on NBC's "Meet the Press," declined to endorse former boss Hillary Clinton while waiting to hear her "vision" for tackling the gap between haves and have-nots.

Progressives need to make income inequality "front and center as an issue in the presidential election," de Blasio said in Milwaukee on Saturday. To help "change the political debate," he told reporters at City Hall after his return, "I've tried to go to some places where I think this message could have an impact."

But de Blasio is little-known beyond New York City, so his capacity to sway heartland Democrats is "marginal at best," said Bob Shrum, a veteran campaign adviser and University of Southern California politics professor.

"He's not John Lindsay, he's not even Ed Koch," Shrum said, citing two former mayors who had outsize personalities and reputations. "He's not a big figure at this point."

advertisement | advertise on newsday

De Blasio played to small crowds of invitees in recent weeks in Wisconsin, Nebraska and Iowa, where he outlined his eight-point plan for the nation with such proposals as raising the minimum wage and providing paid sick leave.

"His visit didn't get as much play here as it might have for someone better known," said Timothy Hagle, a University of Iowa political science professor. "He doesn't seem to be, at this point, as big a name despite being mayor of as big a city as New York."

Even de Blasio's hesitation to endorse Clinton "didn't make a ripple here," said Sue Dinsdale, executive director of the grassroots Iowa Citizen Action Network. "We love to hear progressive voices, but unless you're running for president, you're not going to make a lot of impact here."

Which is not to say that de Blasio hasn't begun to win the respect of some populists who argue he could help make the presidential primaries more competitive by virtue of the office he holds.

"People in San Diego or Topeka may not know who Bill de Blasio is, but it's still really important that the political primary not get shut down prematurely," said Zephyr Teachout, a Fordham Law professor who last year challenged Gov. Andrew M. Cuomo as a progressive alternative.

Get the Newsday Now newsletter!

The best of Newsday every day in your inbox.

Some progressives say de Blasio needs more established credentials, comparing him with Massachusetts Sen. Elizabeth Warren, a populist icon who built a name for herself after the 2008 financial crisis by aiming to break up big banks.

"He is the mayor of New York, which puts him right in the hotbed of Wall Street at a time when Democrats are moving away from Wall Street," said Charles Chamberlain, executive director of Democracy for America, a Burlington, Vermont-based pro-Warren PAC. "This is the area where de Blasio is going to be tested as he moves ahead."

Chamberlain said de Blasio's endorsement for president would be significant to progressives only if it doesn't go to Clinton. De Blasio managed her successful 2000 U.S. Senate campaign, and Chamberlain said "there's a fine line between policy and personal connections" in how a de Blasio endorsement would be viewed.

Independent Sen. Bernie Sanders of Vermont, a self-described "Democratic socialist" who reportedly will announce Thursday a challenge to Clinton for the Democratic nomination, said in a recent interview that de Blasio deserves to be heard.

"He's playing a very important role within the progressive community," Sanders said, because the mayor has implemented initiatives in New York such as expanding the living wage law to help "working people, and that becomes a model for the rest of America."

advertisement | advertise on newsday

De Blasio's coalition of progressives -- which includes Ohio Sen. Sherrod Brown and Connecticut Gov. Dannel Malloy -- will meet again next month in Washington and plans to draft a liberal agreement along the lines of the 1994 Republican "Contract With America." The mayor also is planning a presidential candidates forum on income inequality this fall.

It's more important that de Blasio contribute to the progressive movement than whether he leads it, Teachout said. "The real potential is in him being a part of this network of populist leaders around the country who present a serious alternative to a corporate Democrat."