Bill de Blasio became mayor with a vow to enact New York City's most liberal agenda in a generation, and he's delivered on several signature campaign pledges. But periodic shifts toward the political center have angered and disappointed some of his core supporters.

The rift came into sharp relief Thursday at City Hall as the mayor hosted the Rev. Al Sharpton and black clergy leaders in a summit prompted by the death of Eric Garner after a police officer put him in a banned chokehold.

Outside in the plaza, protesters chanting "N-Y-P-D, keep your hands off of me!" ripped into the "broken windows" theory of policing, which de Blasio and his police commissioner embrace even as they have cast off their predecessors' stop-and-frisk policy.

"I think some people's patience is starting to wear a little thin, and they want to see not just the rhetoric but actual action that shows a commitment to meaningful reform," said Darius Charney, a civil rights lawyer who, after de Blasio became mayor, settled long-running suits on stop-and-frisk and a lack of FDNY minority hiring.

De Blasio has made fidelity to "progressive values" a stock phrase in his speeches, but governing a city of 8.3 million means he can't always satisfy his base, political experts say.

"If you're known as being rigid and unbending, you're not going to be in a position to work well or effectively in a chief executive position," said Kenneth Sherrill, an emeritus professor of political science at Hunter College.

"He understands the nuts and bolts of politics, and he's making very pragmatic decisions," said Doug Muzzio, a Baruch College politics professor.

And down the road, progressive groups may have to take a pragmatic view of another sort -- that de Blasio, whatever his faults in their eyes, will serve their agendas better than any realistic alternative.

To be sure, de Blasio has ushered in progressive change -- making taxpayer-funded prekindergarten classes available for every 4-year-old, mandating paid sick time for most private workers, driving harder bargains with developers to create more affordable housing and launching a plan for municipal ID cards for New Yorkers not in the country legally.

De Blasio spokesman Phil Walzak cited examples such as those to show the mayor is "delivering on what he promised -- a truly progressive agenda that lifts up more people and creates one New York City, rising together."

"Bill de Blasio is the MVP of the progressive movement," said Bill Lipton, the Working Families Party's state director and a longtime de Blasio ally.

But other positions put de Blasio at odds with some on his left flank:

He opposes legalizing marijuana, and police continue to make arrests for possessing small amounts, including in Brooklyn, where the district attorney won't prosecute most such cases.

Besides endorsing Gov. Andrew M. Cuomo, he is backing centrist State Senate Democrats over more liberal challengers.

He staunchly supports Israel -- a common stand for the city's mayors -- but upsetting to progressives sympathetic to the Palestinian cause.

On balance, de Blasio is "more progressive than any mayor ... for a generation," Sherrill said. "What he's doing with the occasional imperfection is upsetting the activist cadre, but it's probably not resonating very much with the average voter."

And even if those activists stay angry in coming years, Iona College politcal science professor Jeanne Zaino said, they face a tough question: "Is there anybody more progressive, more on the left than a de Blasio, who can quite frankly fill his shoes?

"If there's nobody else they're going to be stuck with him," she said.

Woman struck by car dies ... William Floyd Day ... After 47 years, affordable housing Credit: Newsday

Hochul to sign Aid in Dying bill ... Woman struck by car dies ... MTA plans fare, toll hikes ... Let's Go: Williamsburg winter village

Woman struck by car dies ... William Floyd Day ... After 47 years, affordable housing Credit: Newsday

Hochul to sign Aid in Dying bill ... Woman struck by car dies ... MTA plans fare, toll hikes ... Let's Go: Williamsburg winter village

SUBSCRIBE

Unlimited Digital AccessOnly 25¢for 6 months

ACT NOWSALE ENDS SOON | CANCEL ANYTIME