“This is a city that is at a tipping point, at a precipice unlike ever before,” Mr. Espaillat said as he stood next to Mr. Mamdani at the ornate United Palace theater in Upper Manhattan.

Mr. Mamdani will announce on Wednesday that he has hired Jeffrey Lerner, a former political director of the Democratic National Committee and senior Senate aide, to serve as his new communications dir...

“It’s time for every Democratic leader to get on board,” New York co-director Jasmine Gripper told POLITICO, pointing out that Mamdani is supported by fellow state assemblymembers from across the Dem...