Billionaire investor, philanthropist and Democratic Party activist Tom Steyer announced Wednesday he’s running for governor of California.

“I’m running for governor because Californians deserve a life they can afford,” Steyer said in a post on social media. “Sacramento politicians are afraid to change this system. I’m not.”

Steyer, who also made an unsuccessful bid for the Democratic presidential nomination in 2020, joins a crowded field of candidates in heavily Democratic California to succeed Democratic Gov. Gavin Newsom, who is finishing his second and final term and has been positioning himself for a presidential run in 2028.

The Democratic field of contenders for governor include former Orange County Rep. Katie Porter, former U.S. Health and Human Services Secretary and California Attorney General Xavier Becerra, former state Controller Betty Yee and former Los Angeles Mayor Antonio Villaraigosa. Leading Republicans include former Fox News commenter Steve Hilton and Riverside County Sheriff Chad Bianco.

Most polls consistently have shown Porter, who ran for U.S. Senate last year but lost the primary to former Democratic Rep. Adam Schiff, the eventual winner, and Republican baseball star Steve Garvey, leading the field. But Porter’s polling numbers have stalled, and a tense interview with a CBS reporter in October in which Porter threatened to walk out raised questions about her viability.

A November 7 poll by the Berkeley Institute of Governmental Studies found Porter still leading among Democrats, but with support falling to 11% from 17% in August, and notably, trailing the Republican candidate Bianco, who led the field with 13%, up from 10% in August. Poll Director Mark DiCamillo noted that a “huge” 44% of the state’s registered voters remain undecided.

Check back for updates on this developing story.