After more than two decades as one of California's U.S. senators, Barbara Boxer announced Thursday morning that she will not run for re-election in 2016, Politico reported. The veteran liberal Democratic lawmaker made the announcement via a YouTube video. “I am never going to retire. The work is too important. But I will not be running for the Senate in 2016,” Boxer said in the video

The announcement was produced in the style of an interview, conducted by her eldest grandson, Zach Rodham, who is also Hillary Rodham Clinton's nephew. The announcement was the first thing posted to Boxer's Twitter account since Nov. 18. But the 74-year-old senator has been as active as ever on many political issues, including climate change, health care and U.S. foreign policy.

The retirement, which was widely expected by insiders since Boxer had not been raising campaign funds, will shake up California’s Democratic politics, setting up a wide-open primary for a seat Boxer has held since 1993, reported Politico. Californians will also lose in Boxer one of Senate Democrats’ top environmental voices. Boxer stood firm on a waning party position that the Keystone XL pipeline be studied further, after nearly a dozen of her Democratic colleagues last year insisted the Obama administration had been given enough time for the study, the San Francisco Chronicle reported. Republicans in the new GOP-controlled Congress have vowed to ram approval of the pipeline through both chambers, in spite of President Barack Obama's threat of veto. In fact, a Senate committee passed the Keystone bill Thursday.

Boxer, a New York City native, was a stockbroker and a supervisor on the governing board of Marin County, California, north of San Francisco, before taking up national politics, the Sacramento Bee reported. She began her national political career in the U.S. House of Representatives in 1982, representing California's 6th District in Sonoma and Marin counties. Ten years later, she was elected to the U.S. Senate, replacing Democrat Alan Cranston. As a senator, Boxer has been a member of more than a handful of high-profile committee, including the Senate Committee on Foreign Relations.

Among Democrats, state Attorney General Kamala Harris, Lt. Gov. Gavin Newsom and Los Angeles Mayor Eric Garcetti have been mentioned as possible candidates. The Republicans have not won a U.S. Senate race in California since 1988.