

I mean it’s already happened/is happening. Plenty have refused to endorse and some have outright opposed him because of Israel and his skin color (see NY gov Hochul, Senator Schumer, and Senator Gillibrand). However, both AOC and Bernie have endorsed him. Unless Obama comes out against I’m not sure that what democrats outside of NY much less NYC say will really sway anyone more.
Mamdami is WFP (working families party) endorsed and they’ve been going to bat for him too in their newsletters. While 3rd party is more viable in NY its primarily in an endorsement type thing as candidates can run under multiple parties (thus listed multiple times on the same ballot) and you choose the party you vote for them under. Theoretically, this gives the 3rd party more sway in pushing policies but it is rarely straight 3rd party candidates. Unsure if the city has more 3rd parties I’m unaware of (there’s Republican, Democrat, Conservative, and WFP).