WASHINGTON - Former union leader and Democratic insider Laphonza Butler was sworn in as the newest member of the Senate on Tuesday, replacing California Sen. Dianne Feinstein after her death and becoming only the third Black female senator in history.

Sen. Butler was appointed by California Gov. Gavin Newsom on Sunday, just two days after Feinstein died at her home in Washington. Sen. Butler is a longtime fundraiser and strategist in the state’s Democratic circles and was the head of Emily’s List, a national organization that raises money for women candidates who support abortion rights.

The new senator was sworn in by Vice President Kamala Harris, who served as the second Black female senator until she resigned in 2021 to join President Biden in the White House. The first was Democratic Sen. Carol Moseley Braun of Illinois, who served one term in the 1990s.

With dozens of supporters and family members looking down from the gallery, Sen. Butler smiled broadly as she walked down the center aisle of the Senate alongside Democratic Sen. Alex Padilla of California and Senate Majority Leader Chuck Schumer.

After Vice President Harris administered the oath of office, members of the Senate from both parties crowded around her to shake her hand.

Sen. Schumer said Sen. Butler has “dedicated her entire career to fighting for others — fighting for women, fighting for working families and fighting for the cause of justice.” After she was sworn in, President Biden called her to congratulate her, the White House said. The Congressional Black Caucus also held a ceremonial swearing-in for Sen. Butler.

“Her background and years of experience will bring a much-needed perspective to the Senate, which currently does not have any Black women,” CBC Chairman Steven Horsford, D-Nev., said in a statement after she was appointed.

Sen. Butler also is the first openly LGBTQ+ senator from California.

Though she has never held elective office, Gov. Newsom praised her “deep knowledge” of the legislative process and said she was the kind of candidate he would build “if I had to literally design from my imagination.”

“She’s the only choice,” Gov. Newsom added.