But in taking on Cuomo, a Democrat, Nixon faces a tough primary against a two-term governor with nearly universal name recognition in the state and a $30 million war chest.
Should she run, Ms. Nixon is expected to challenge Mr. Cuomo from the political left.
The 51-year-old actress Monday afternoon announced her candidacy in a video posted to social media. Her bid comes on the heels of speculation that TV host Oprah Winfrey was planning to challenge former reality TV star Donald Trump for the presidency in 2020 - a rumor Winfrey later denied. The Democratic Primary will be held on September 13, and Cuomo - a potential presidential candidate for 2020 - is running for his third term as governor. Expect to see a little more of Nixon between now and then. The margin of error is plus-minus 4.0 percentage points.
"It could be a fight for the soul of the Democratic Party in some sense", said Baruch College political scientist Douglas Muzzio.More news: Putin thanks voters for election triumph
Cynthia Nixon announced her run for governor of New York Monday.
"Cynthia Nixon has been an incredible champion of public schools, and she is a progressive Democrat".
Mr. Greenberg noted that Mr. Cuomo's job-approval rating did slide to 42 percent, with the percentage of NY voters who said he was doing a poor job rising to 25 percent, equaling the high in a Siena College poll.
In an opinion poll conducted by Siena College before the announcement, Mr Cuomo had a lead of 66% to 19% over Nixon.
"Unlike Governor Cuomo, Cynthia Nixon rides the subway every day", it says on Nixon's website.
The first task for Nixon, Muzzio said, is to launch a listening and talking tour.
A spokesman for the governor said afterward that Cuomo was just trying to have a bit of fun, and was not linking Nixon to the Russian leader.