A new nonprofit aims to harness the grassroots momentum of Zohran Mamdani’s successful mayoral campaign as he takes office, following a similar path to Mayor Bill de Blasio that sparked corruption investigations and criticism from good government groups.

More than 650 people joined the first hour-long “mass call” Thursday night for Our Time, which is classified as a tax-exempt 501c4 social welfare organization. While technically separate from Mamdani and his incoming administration, the group can fundraise and lobby for his policies. Our Time plans to launch a round of campaign-style door-knocking next weekend to build support for Mamdani’s campaign promises, starting with universal child care.

“ Our mission at Our Time is to continue to grow the movement that we began building so that we can win, implement and defend the affordability agenda,” Jeremy Freeman, the new executive director told participants on the call, which was available in English, Spanish and Bangla.

The use of nonprofits to support mayoral issues is not new in New York City. Former Mayor Michael Bloomberg also utilized a nonprofit, the Mayor’s Fund, to promote the public-private partnerships central to his agenda.

Our Time is more reminiscent of de Blasio’s Campaign for One New York, which became embroiled in protracted state and federal investigations over the role the mayor played in its fundraising.

While prosecutors never charged anyone from the de Blasio administration with wrongdoing, both the Southern District of New York and Manhattan district attorney’s offices issued memos admonishing the de Blasio administration for his fundraising practices and for soliciting donations from people with business before the city seeking favorable treatment.

Our Time organizers — all of whom are former Mamdani campaign volunteers -- said they are studying those previous efforts to avoid pitfalls.

But John Kaehny, executive director of the watchdog group Reinvent Albany, said Mamdani and his supporters should tread carefully.

“ The potential for pay-to-play is always a concern, even when you have a young, idealistic democratic socialist mayor,” Kaehny said.

Freeman, a former neuroscientist who helped build some of the data tools used by the Mamdani campaign, said Our Time will conduct its own fundraising and aims to be more transparent than the law requires.

He said they will not accept donations from entities with business before the city. The group also plans to publish the names of any donors who give more than $1,000 on their website.

No names are listed on the site. The group was only formed a month ago.

Many of the volunteers said after Mamdani’s victory, they felt deeply invested in proving he could manage the city and deliver on his promises. A sustained wave of civic engagement could be critical to fulfilling the young democratic socialist leader’s lofty goals.

Participants on the mass call raised questions about how Our Time would be different from previous organizations, like Organizing for America, which was founded by former President Barack Obama’s supporters after he was elected in 2008. Observers have criticized that effort for weakening local Democratic Party organizations and failing to stop a surge of Republican wins at the state and local levels.

“I think the key difference is they didn’t continue the organizing that helped power them to victory,” said Divya Sundaram, a former Mamdani volunteer, housing rights advocate and Our Time’s new deputy executive director. “Organizing and field are going to be at the heart of a lot of our work.”

Former Mayor Bill de Blasio's administration faced investigations tied to his Campaign For One New York.

Starting next weekend, the group plans to dispatch hundreds of volunteers to 17 different neighborhoods across the city to knock on doors in support of universal child care and ask voters to send letters of support to their state lawmakers. They plan to team up with the NYC Democratic Socialists of America’s child care working group on the effort. In the coming months, they aim to recruit some 15,000 volunteers for a trip to Albany to lobby state lawmakers.

They’re also planning a week of action in January, along with NYS Tenant Bloc, to push for a rent freeze and day of action in February along with Riders Alliance to fight for free, fast buses.

“Once we win that and once we prove that Zohran can be successful, we have to think about all the other things we need to make New York affordable and accessible,” Sundaram said.

But the line between the Mamdani campaign and this new offshoot is already blurred. Our Time’s logo evokes the mayor-elect’s taxi-cab yellow, blue and drop-shadow red campaign aesthetic. The Mamdani campaign donated its list of volunteers to the new nonprofit, Freeman said.

Among the guest speakers on Thursday night’s call was Lina Khan, who was the federal trade commissioner under former President Joe Biden and is co-chair of Mamdani’s transition committee.

“ It goes without saying that some of the most powerful people in the country would love nothing more than for the mayor-elect and his team to fail,” Khan said.

She said the support of outside groups was essential to advance Mamdani’s agenda.

“ The bottom line here is that in many ways our collective work has only just begun,” Khan said.

Susan Lerner, executive director of another good government group, Common Cause New York, appreciated the effort to keep Mamdani’s supporters engaged. But she was wary of Our Time’s structure.

“I am always supportive of high energy organizing efforts,” Lerner said. “But my preference is to have that energy in the service of government directly, not some outside shadow agency.”

Still, Freeman said he and the Our Time team, which includes only four paid staffers, aim to recreate the same kind of civic — and social — actions that helped propel the Mamdani campaign.

“My experience in the city during the Zohran campaign is that coming to a Zohran canvas on the weekend is the thing that all your friends asked if you were doing,” said Freeman. “We want the Our Time canvasses to be the ‘the thing’ that everyone talks about going to.”