U.S. Sen. Dianne Feinstein, an advocate for liberal priorities, dies at age 90

Dianne Feinstein, whose three decades in the Senate made her the longest-serving female U.S. senator in history, has died, according to a source familiar.

U.S. Sen. Dianne Feinstein of California, a centrist Democrat who was elected to the Senate in 1992 in the "Year of the Woman" and broke gender barriers throughout her long career in local and national politics, has died. She was 90.

Feinstein died on Thursday night at her home in Washington, D.C., her office confirmed on Friday.

President Joe Biden, a fellow Democrat, called Feinstein "a pioneering American," a "true trailblazer" and a "cherished friend" for him and first lady Jill Biden.

"Dianne made her mark on everything from national security to the environment to protecting civil liberties," Biden said in a statement. "She's made history in so many ways, and our country will benefit from her legacy for generations."

Feinstein, the oldest sitting U.S. senator, was a passionate advocate for liberal priorities important to her state -- including environmental protection, reproductive rights and gun control -- but was also known as a pragmatic lawmaker who reached out to Republicans and sought middle ground.

She was elected to the San Francisco Board of Supervisors in 1969 and became its first female president in 1978, the year Mayor George Moscone was gunned down alongside Supervisor Harvey Milk at City Hall by Dan White, a disgruntled former supervisor. Feinstein found Milk's body.

After Moscone's death, Feinstein became San Francisco's first female mayor. In the Senate, she was one of California's first two female senators, the first woman to head the Senate Intelligence Committee and the first woman to serve as the Judiciary committee's top Democrat.