She said she will continue to work for progressive causes and stay active in Democratic politics.
"I'm going to continue working on the issues I love," Boxer said. "I'll have more time to help more people through my PAC for a Change community. I have to make sure this Senate seat stays progressive -- that is so critical -- and I want to help our Democratic candidate for president make history."
"But you know what?" she says to her grandson in the video. "I want to come home. I want to come home to the state I love so much, California."
Boxer, who started her political career in Marin County and moved from Greenbrae to the Coachella Valley in 2006, has served as chair of the Senate Environment and Public Works Committee, made her announcement just days after a new Republican majority took control of the upper house.
The senator, something of a connoisseur of limericks and doggerel verse, ended the video with a rhyme:
The Senate is the place where I’ve always made my case.
For families, for the planet and the human race.
More than 20 years in a job I love,
Thanks to California and the Lord above.
So although I won’t be working for my Senate space,
And I won’t be running in that next tough race,
As long as there are issues and challenges and strife,
I will never retire because that’s the meaning of my life.
Boxer's departure means that California will have its first open Senate race -- one not involving an incumbent -- since her race against Republican Bruce Herschensohn in 1992.
Her announcement will touch off what's likely to be an expensive scramble to succeed her, and a host of Democrats are among those that pundits see as likely candidates for the seat. A summary of the possible field from the Washington Post:
Rumored candidates include Lt. Gov. Gavin Newsom, Attorney General Kamala Harris, Rep. Jackie Speier (D-San Mateo), billionaire climate activist Tom Steyer, current Los Angeles Mayor Eric Garcetti and former Los Angeles Mayor Antonio Villaraigosa.
The last California Republican to serve in the Senate was John Seymour, a state senator from Orange County appointed to fill Sen. Pete Wilson's seat when Wilson was elected governor in 1990. Wilson won the governorship in a close race with Dianne Feinstein, the former mayor of San Francisco. Feinstein then ran against Seymour in a special election to complete Wilson's Senate term and won handily.