Ramos, who is also running for mayor, says she is staying in the race and will remain on the ballot in order to keep having a voice to advocate for her causes.
The endorsement comes as an acknowledgement by Ramos that she will not win the primary election.
"Raising the minimum wage, building truly affordable housing, delivering for workers and immigrants -- those still need a champion, and I know with Andrew we can deliver," Ramos said at a morning news conference at the Carpenters Union.
The progressive state senator, who represents parts of Queens, has been critical of the former governor in the past, even questioning his mental acuity.
"I need to say it, he's not the same man I knew as governor," Ramos said back in March. "His spine is not as strong as it once was. Andrew Cuomo won't stand up to Trump because he's too busy running away from his own record."
Cuomo seemed to laugh it off on Friday.
"People say things in campaigns. I've said a lot of things about opponents. You get caught up in the energy of the moment, and that's the nature of the business," Cuomo said.
Ramos was hoping to draw the union support that has backed Cuomo since he entered the race.
The two faced off alongside other candidates on the debate stage Wednesday night. Fellow candidate Brad Lander was at a loss to explain it.
"All I can say is we've been on the campaign trail together a lot and she's been making a very good case against Andrew Cuomo," Lander said.
Ramos says she's hoping to put the brakes on Queens Assemblyman Zohran Mamdani, whose campaign is closing the gap on Cuomo. But she was among the leading voices calling for his resignation when Cuomo was accused of sexual harassment, allegations Cuomo has denied.
"This is not about forgiveness. This is not about forgetting anything," Ramos said. "This is a very sober view of being one week away from early voting and understanding that there are two clear people heading the race, and I want to make sure that we have a mayor that understands how government works."
Meanwhile, protesters in Lower Manhattan disrupted a press conference held by Mamdani.
A demonstrator in a "Make America Great Again" cap confronted the lawmaker about his views on Israel. Afterwards, Mamdani reacted to Ramos' endorsement of Cuomo.
"I'm disappointed to see any endorsement for Andrew Cuomo, because ultimately Andrew Cuomo is the best example of the kind of leadership that has failed New Yorkers and brought us to this point where we are in the most expensive city in the United States of America," Mamdani said.
Earlier this week, Mamdani secured the endorsement of Congresswoman Alexandria Ocasio-Cortez as her top choice for mayor.
Early voting in the New York City mayoral primary begins next Saturday on June 14.
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