The decision by Ms. Ramos, a state senator from Queens, is at odds with her frequent criticism of Andrew M. Cuomo, including comments questioning his “mental acuity.”

Andrew Cuomo faced a two-hour pile-on Wednesday as eight other Democrats vying for the party’s nomination for New York City mayor spent their first debate attempting to knock the former governor off his perch.

The most populated city in the United States might also have the most polarizing mayoral race of any other. The New York City mayoral race features a disgraced former governor, a surging socialist, an incumbent with his own legal troubles, and other heavy hitters.