California Attorney General Kamala Harris is seeking the Senate seat being vacated in 2016 by Democrat Barbara Boxer, who will retire after 33 years in Congress.
With her bid, announced online Tuesday, Harris becomes the first Democrat to enter what promises to be a wide-open contest that is expected to be among the most expensive Senate campaigns of 2016.
Billionaire environmental activist Tom Steyer, another Democrat, said he planned to decide shortly if he would become a candidate. Meanwhile, another prominent Democrat, former Los Angeles Mayor Antonio Villaraigosa, was consulting with advisers in preparation for a possible run.
Tom Del Beccaro and Duf Sundheim, two former chairmen of the California Republican Party, are also considering runs for the office.
Democrats are well-positioned to retain the Senate seat in the state where the party controls every statewide office and both chambers in the Legislature.
Allan Hoffenblum, publisher of the California Target Book, a political almanac, said Harris remains relatively unknown in parts of the state, and he expects someone from the Hispanic community and the business sector to seek the office.
"There's just too many egos and ambitions out there," Hoffenblum said. "If Kamala Harris does clear the field, I wouldn't be surprised if the business community, which doesn't really want another Barbara Boxer going to Washington, looks for somebody who would run as (an independent) candidate."
The 50-year-old Harris, the first woman and first minority to serve as California's top prosecutor, called herself a fighter in her online announcement — echoing a mantra often used by the liberal Boxer during her campaigns. The announcment came with a box that supporters could click if they wanted to donate to her campaign.
California Lt. Gov. Gavin Newsom, whose support for same-sex marriage while mayor of San Francisco spurred a wave of social and political change, said on Monday he would not run for Boxer's seat.
Harris is a former San Francisco district attorney who is now in her second term as attorney general. She drew national attention as a tough negotiator after the mortgage meltdown, when she pushed for and won concessions from major banks in a nationwide settlement aimed at helping consumers who had lost their homes to foreclosure.
Harris also sponsored the state's Homeowners Bill of Rights, which sets rules for foreclosures.