I had no idea he would turn out to be this impressive.
It is hard to find good data on the polls but I think Mamdani has been expanding his electorate beyond his initial base of support.
I did find this article about a poll on Cuomo's lead shrinking.
Andrew Cuomos lead over Zohran Mamdani shrinking in final stretch of NYC mayoral race: poll
(snip)
Another significant finding in the new poll is that Mamdani has expanded his support among Latino voters by broad margins, earning 41% support from that constituency, a 21% increase from his levels in the May survey. Cuomos support among Latinos, meanwhile, decreased to 36% from 41%, according to the new poll.
The boost in Latino support for Mamdani comes after New York Rep. Alexandria Ocasio-Cortez, one of the Democratic Partys most popular figures, endorsed him as her No. 1 pick on June 5.
Mamdani, whos running on a left-wing platform that includes promises to expand free childcare and freeze rent for stabilized tenants, has also aired Spanish language ads in recent weeks.
https://www.nydailynews.com/2025/06/18/andrew-cuomos-lead-zohran-mamdani-shrinking-final-stretch-nyc-mayoral-race-poll/
I'm also interested in over 50 and under 50 as there may be a big difference there but Mamdani started with almost 0 name recognition compared to Cuomo.