Here are the people who have endorsed him from his page:

https://www.zohranfornyc.com/endorsements

Then there’s organized labor. Most of the city’s major labor unions have already endorsed Mamdani. A total of 67 unions and political organizations, along with nine state senators, 17 assembly members and 16 council members, or roughly one-third of the City Council, have thrown their support behind him.

https://abc7ny.com/post/nyc-mayoral-race-zohran-mamdani-failing-secure-endorsement-top-democrats-like-kathy-hochul-hakeem-jeffries/17665962/