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.”

The progressive congresswoman is supporting the young Queens assemblyman’s upstart campaign in a crowded Democratic primary field.

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.