Nearly all the men and women running to be New York City’s next mayor came together on Sunday to urge voters not to support the candidates’ shared opponent, former Gov. Andrew M. Cuomo.

The group — which ranged in ideology from Zohran Mamdani, a democratic socialist, to Curtis Sliwa, a Republican — gathered to mark the fifth anniversary of a New York State Department of Health order, issued while Mr. Cuomo was governor, that directed nursing homes to readmit hospital patients who had tested positive for the coronavirus. The order, patients’ families and lawmakers have said, contributed to thousands of Covid-related deaths among nursing home residents in the state.

For Mr. Cuomo, a Democrat who resigned in 2021 amid a sexual harassment scandal, continued scrutiny of his pandemic response and his administration’s efforts to conceal the true death toll in nursing homes was a political millstone even before he entered the mayor’s race. He has sharply defended his handling of the crisis and has called the criticism politically motivated.

On Sunday, nine mayoral candidates stood on a street in Brooklyn’s Cobble Hill neighborhood in front of a memorial wall that displayed photos of nursing home residents who died during the Covid crisis. Each candidate said that they were not attending for political reasons, while taking the opportunity to criticize the former governor, who is leading in the polls. The event was organized by families who have long called for Mr. Cuomo to apologize and take responsibility for their relatives’ deaths.

“This is not about partisan politics, but it is about accountability,” said Brad Lander, the city comptroller who is running in the Democratic primary in June. “It is not too much to ask Andrew Cuomo to meet with families.”