"One of the things that's been great about Zohran's campaign is he has a romantic view of what the city can be and should be," Heastie said. "And, you know, sometimes people want to be romanced."
The endorsement comes on the heels of Governor Kathy Hochul's opinion piece declaring her support for Mamdani.
It was a scene of unity on Wednesday morning between Heastie and Mamdani, who know each other well.
Affordability is the main message resonating with voters, and Heastie said that includes raising taxes on millionaires, passing free child care and free buses.
"If you notice over the years, the number one population leaving New York has been Black, African-American, Caribbean because of affordability," Heastie said. "Zohran's message has really translated into people's consciousness that we actually have to have a place that people can afford to live."
Heastie said they have served together for five years in the Assembly and that Mamdani shared his plans of running for mayor very early on.
"As we celebrate this moment, Speaker Heastie's endorsement of our campaign, we do so in front of a great testament to so much of what Carl's politics are, they are a reflection of a love and a dedication to the people of this district and the ability to get things done," Mamdani said.
Other party heavyweights, including House Minority Leader Hakeem Jeffries and Senate Minority Leader Chuck Schumer, have yet to follow Hochul's lead in backing the projected frontrunner.
"Others will have to make their own decisions for their own reasons," Hochul said when asked whether her endorsement would influence other Democrats.
However, Rep. Yvette Clark, the chair of the Congressional Black Caucus, is expected to follow suit and endorse Mamdani next Monday.
In a new Marist poll released this week, Mamdani leads the group of candidates with 45%.
The next closest is former Gov. Andrew Cuomo with 24%, followed by Curtis Sliwa with 17% and incumbent Mayor Eric Adams in last with 9%. Five percent of likely voters say they're undecided.
The poll also looked at what may happen if the race came down to just Mamdani and Cuomo.
In that race, 49% of likely voters would support Mamdani while 39% would back Cuomo.
The former governor continues to attack Mamdani, insisting a socialist mayor is a threat to New York.
"They know that you have a socialist and you have a Democrat, and that's apples and oranges. And it's a very clear choice," Cuomo said.
On Wednesday, Cuomo met with chamber of commerce leaders in the Financial District.
"I laid out a program on how we can grow small businesses, facilitate small businesses, and create more jobs," he said.
Mayor Adams visited a fair for seniors on the Upper East Side on Wednesday morning, organized by his Department for the Aging. The mayor doubled down on recent comments, critical of some of Mamdani's supporters, while insisting that the candidate should rein them in.
"I'm seeing this every day, this real mean, nasty, angry approach, it turns into curses someone out. then it turns into giving them the finger," Adams said. "Then it turns into pushing and shoving and there's no telling where it goes. And so, yes, he should stand up. He wants to be the mayor, the leader of this entire city, not part of the city."
Meanwhile, Republican nominee Curtis Sliwa attended a court appearance for a man accused of animal cruelty.
"When I'm elected mayor on Day One, January 1st, 2026, we are establishing an animal welfare division in the basement of City Hall," Sliwa said.
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