By Saba Hamedy, CNN

(CNN) -- After much speculation, actress and activist Cynthia Nixon announced Monday that she is officially throwing her hat in the New York gubernatorial race.

"I love New York, and today I'm announcing my candidacy for governor," she tweeted Monday, along with a video.

"I've never lived anywhere else," Nixon says in the video. "But something has to change. We want our government to work again, on health care, ending mass incarceration, fixing our broken subway. We are sick of politicians who care more about headlines and power than they do about us. It can't just be business as usual anymore."

The "Sex and the City" star will challenge Democratic Gov. Andrew Cuomo in the state's Democratic primary in September.

Nixon is forming a team of alumni of the New York political sphere, including Rebecca Katz and Bill Hyers -- who worked on New York City Mayor Bill de Blasio's first campaign -- to help her ahead of the primary. Katz will work on the campaign as a senior strategist. Nicole Aro, who recently worked as the American Federation of Labor and Congress of Industrial Organizations' director or digital strategies, will serve as campaign manager.

The Tony, Grammy and Emmy Award-winner was among the star-studded cast of actors, entertainers and activists who came together for "the People's State of the Union" in January, an alternative event to President Donald Trump's first State of the Union speech.

"Our democracy is under attack, and we Americans need to cherish and to fight for it," Nixon said during her speech.

The mother of three, who is married to activist Christine Marinoni, has also been vocal about education issues, and she served on de Blasio's advisory board for the Mayor's Fund to Advance New York City. She was recently honored by the Human Rights Campaign with its Visibility Award for her work advocating for marriage equality and fighting stigma and prejudice.

In a January op-ed for CNN, Nixon wrote: "If we've learned anything during this first year of the Trump presidency, it's that the cavalry isn't coming to save us. We ourselves are the cavalry. In 2018, each one of us has to do whatever we can to take the government back. If we want change, we have to go out ourselves and seize it."

Nixon's campaign said in its press release that the candidate will spend the coming weeks traveling across the state to hear from voters.

Nixon's entry into the race could split state progressives, who have felt burned by Cuomo's leadership in Albany and repeated clashes with de Blasio.

Reached on Monday, the New York Working Families Party, which backed Cuomo in 2014 after a contentious internal debate, told CNN they hadn't yet reached a decision for 2018.

"Our endorsement in the Governor's race will be determined by our state committee, which is comprised of 232 labor, community and grassroots activists from across New York State," said New York WFP director Bill Lipton. "Stay tuned."