U.S. Sen. Dianne Feinstein of California has died at age 90, her office confirmed Friday.

Feinstein, a Democrat, was the oldest member of the Senate, where she served since 1992. She held her seat in the chamber longer than any other woman, and any senator from California.

She passed away Thursday night at her home in Washington, D.C.

“There are few women who can be called senator, chairman, mayor, wife, mom and grandmother. Senator Feinstein was a force of nature who made an incredible impact on our country and her home state,” her chief of staff James Sauls said in a statement.

Feinstein’s death ends a boundary-pushing political career that spanned more than half a century, which was studded with major legislative achievements on issues including gun control and the environment.

In Feinstein’s final years, she had increasingly visible health and memory issues, and a conflict with her fellow Democrats over her refusal to step down.

She had planned to retire at the end of her current term in 2024.

Feinstein’s death leaves vacant her powerful Senate seat, requiring Gov. Gavin Newsom to appoint a temporary successor.

Newsom in a statement called Feinstein “a political giant, whose tenacity was matched by her grace.”

“She broke down barriers and glass ceilings, but never lost her belief in the spirit of political cooperation,” he said. “There is simply nobody who possessed the poise, gravitas, and fierceness of Dianne Feinstein.”

“Jennifer and I are deeply saddened by her passing, and we will mourn with her family in this difficult time.”

Senate Majority Leader Chuck Schumer, D-N.Y., is set to address Feinstein’s death on the Senate floor Friday.

“It’s a very, very sad day,” he told NBC.

Rep. Nancy Pelosi of California, the former speaker of the House, grew emotional as she told reporters, “It’s a very sad day for all of us.”

“May she rest in peace,” Pelosi said.

A San Francisco native, Feinstein cleared a path for women in politics as she rose the ranks of leadership. After two failed bids for mayor, she was elected president of San Francisco’s board of supervisors in 1978, becoming the first woman to hold the title.

Feinstein was made acting mayor of the city later that year, after then-Mayor George Moscone and Harvey Milk, her colleague on the board of supervisors, were assassinated by Dan White, a former member of the same board.

In later interviews, Feinstein recalled finding Milk’s body and searching for a pulse by putting her finger in a bullet hole.

Feinstein was the first to announce the murders to the press. She was appointed mayor a week later, again becoming the first woman elevated to the office.

The tragedy had the side effect of jumpstarting Feinstein’s political career, but the trauma of the day stuck with her even decades later. 

“I never really talk about this,” Feinstein said with a sigh when asked about the murders in a CNN interview in 2017.

Her streak of firsts continued at the national level. Feinstein lost a gubernatorial bid in 1990, but two years later won a special election to the U.S. Senate, becoming California’s first female senator.

Weeks later, the state’s second female senator, Barbara Boxer, was sworn into office, making California the first state in the U.S. to be represented in the Senate by two women. 

Their 1992 elections helped define the “Year of the Woman,” in which four Democratic women were newly elected to the Senate — more than doubling the chamber’s female representation.

In the Senate, Feinstein clinched some of her biggest legislative achievements. She wrote and championed the 1994 assault weapons ban, both a landmark bill and a continuation of a career-long effort to enact stricter gun controls. 

The legislation passed Congress and was signed by then-President Bill Clinton, albeit with major compromises including a 10-year sunset provision. The ban expired in 2004 during the administration of George W. Bush.

She also sponsored bills that protect millions of acres of California’s desert, worked to create a nationwide AMBER alert network, helped reauthorize the Violence Against Women Act and fought for the release of a lengthy report detailing the CIA’s torture practices, among other accomplishments.

Over her three decades in the Senate, Feinstein has generally been seen as a political moderate in her party. In the 1990s and 2000s, that reputation made Feinstein highly popular — but much of that popularity eroded in the proceeding years as California’s political tint shifted toward deeper shades of blue.

As her centrism grew increasingly out of fashion, Feinstein’s standing in her final stretch in office was further diminished by a crescendo of skepticism about her mental fitness for the Senate.

A damning report from the San Francisco Chronicle in April 2022 featured unnamed Democratic colleagues of Feinstein fretting over her apparent decline in mental acuity. Feinstein defended her ability to govern, while acknowledging that she had been going through an “extremely painful and distracting” period as her late husband, financier Richard Blum, had battled cancer.

By the time Feinstein announced that she would not seek reelection at the end of her term in 2024, multiple Democratic politicians had already launched campaigns to succeed her.