Dianne Feinstein, 89, won't seek re-election, opening up a California Senate seat in 2024

Sen. Dianne Feinstein of California announced Tuesday that she will retire at the end of her current term, setting up a major Democratic competition for her coveted seat.

Feinstein, who at 89 is the oldest sitting U.S. senator and the longest-serving senator from her state, said she intends to "accomplish as much for California as I can through the end of next year when my term ends."

"Even with a divided Congress, we can still pass bills that will improve lives," Feinstein said in a statement.

The fight for the open Senate seat in the powerful, reliably blue state of California promises to be one of the most competitive — and expensive — races of the 2024 election cycle.

While Feinstein's announcement officially puts her seat in play for the 2024 election cycle, multiple California Democrats had already launched Senate campaigns weeks earlier.

Rep. Katie Porter was first out of the gate, announcing her Senate bid on Jan. 10 and touting an endorsement from Sen. Elizabeth Warren, D-Mass., soon after.

Rep. Adam Schiff, the former chairman of the House Intelligence Committee, threw his hat in the ring late last month.

Those candidates have projected deference toward Feinstein, even as they entered the race to succeed her prior to the announcement of her widely anticipated retirement.

"She has so much to teach all of us," Porter said of Feinstein last month, adding that she had tried to reach out to the senator before launching her Senate campaign.

Former House Speaker and current Rep. Nancy Pelosi, D-Calif., earlier this month issued a qualified endorsement of Schiff that heaped praise on Feinstein and vowed to back her if she decided to run again.

More California Democrats, including Reps. Barbara Lee and Ro Khanna, are expected to announce their Senate campaign plans soon.

Feinstein's career as a a political leader got a morbid jumpstart in 1978, when she became acting mayor of San Francisco following the assassination of the city's then-mayor, George Moscone, and Board of Supervisors member Harvey Milk. She was appointed soon after, becoming San Francisco's first female mayor.

After a failed gubernatorial bid, Feinstein was elected to the U.S. Senate in a special election in 1992. She was reelected in 1994 to the first of five full terms. In 2021, she became California's longest-serving senator. She became the longest-serving woman in U.S. Senate history on in November.

Feinstein's political career is distinguished with a number of firsts for women: The first female mayor of San Francisco, the first woman to chair the Senate Rules and Intelligence committees, the first woman to oversee a presidential inauguration.

Her retirement announcement on Tuesday afternoon referenced a number of her legislative accomplishments, ranging from the 1994 Assault Weapons Ban to her oversight of the CIA's interrogation policies, which led to the passage of anti-torture legislation.

In her final stretch in the Senate, Feinstein vowed to continue working on issues such as California's homelessness crisis and its struggles with droughts and wildfires, as well as health-care access

"Congress has enacted legislation on all of these topics over the past several years, but more needs to be done – and I will continue these efforts," she said in the statement.

She vowed to continue her fight against gun violence, to preserve "our pristine lands" and promote economic growth, adding that she would use her position on the powerful appropriations committee to ensure the state received its fair share of federal funding.

"Each of us was sent here to solve problems," she said. "That's what I've done for the last 30 years, and that's what I plan to do for the next two years. My thanks to the people of California for allowing me to serve them."