Gov. Andrew M. Cuomo is entering his re-election campaign with a commanding lead over both his Republican rivals and a possible Democratic primary opponent, the actress Cynthia Nixon, according to a new poll from Siena College.



The survey shows Mr. Cuomo ahead of Ms. Nixon among Democratic voters by 66 percent to 19 percent. He leads her by a wide margin among every subgroup in the survey: men and women, moderates and liberals, black, white and Latino voters, upstate and New York City residents.

Best known for her role in “Sex and the City,” Ms. Nixon entered the contest only Monday, after the poll had been completed, but had said she was exploring a bid and had been in contact with political strategists with experience running progressive campaigns. A longtime education activist in the state, Ms. Nixon has the benefit of name recognition, and yet remains broadly unknown to voters, with 60 percent saying they had no opinion of her.

The poll showed Mr. Cuomo with a two-to-one advantage over both his potential Republican challengers, State Senator John DeFrancisco and Marc Molinaro, the Dutchess County executive, who is expected to formally declare his candidacy at the beginning of April.