In the months before he joined New York City’s mayoral race, Andrew M. Cuomo sought to create as much distance as possible from the sexual harassment scandal that forced him to resign as governor more than three years ago.

But with his entry on Saturday, some of his challengers in the race and the women who accused him are determined to keep the allegations front and center.

Brad Lander, the city comptroller who is running for mayor, plans to hold a news conference in the coming days with Erica Vladimer, who represents a group that combats sexual harassment in Albany.

Lindsey Boylan, a former aide who accused Mr. Cuomo of an unwanted kiss, has stepped up attacks of him on social media.

A left-leaning coalition has already released radio ads portraying Mr. Cuomo, a Democrat, as a predator, and will target him through a new super PAC. One ad said the former governor “harassed and intimidated the women who dared to speak out” against him.

Mariann Wang, a lawyer for Brittany Commisso, who accused Mr. Cuomo of groping her while she worked in his office, said in a statement: “An unrepentant sexual harasser who resigned in disgrace and who has spent the past four years spending millions in taxpayer money to vindictively litigate against his victims should not be the mayor of New York City.”