Nancy Kassebaum Baker, a pioneering Republican senator from Kansas and the first woman elected to the U.S. Senate without having a spouse who previously served, has died. She was 94.

Kassebaum Baker died Friday of natural causes, according to her son, Bill Kassebaum. She served three terms in the Senate, from 1978 to 1997, representing Kansas with a moderate and independent-minded approach.

Known for her collegial style, Kassebaum Baker often worked with senators across the political spectrum. A notable bipartisan achievement was a 1996 health insurance law that bore her name and that of Sen. Ted Kennedy. She was also recognized for her support of some gun control measures, including a ban on assault weapons championed by President Bill Clinton.

Born July 29, 1932, Kassebaum Baker was the daughter of Kansas Governor Alf Landon, who was the Republican nominee for president in 1936. She earned degrees from the University of Kansas and the University of Michigan. Before entering politics, she worked as a radio-station executive and served on a local school board.

She entered the Senate race in 1978, campaigning as Nancy Landon Kassebaum. She won the Republican nomination with less than 31% of the vote in a crowded primary and went on to defeat former Congressman Bill Roy in November. Her victory brought her national attention as one of the few women in the Senate at the time. She chaired the Senate Labor and Human Resources Committee, the only woman senator to chair a committee during her tenure.

Kassebaum Baker won re-election twice, securing 76% of the vote in 1984 and 74% in 1990. Despite her popularity, her voting record, particularly her support for the assault weapons ban, sometimes frustrated conservative activists.

She decided not to seek a third term in 1996, expressing a desire to return to her ranch in Kansas and spend time with her grandchildren.

In 1996, she married former Tennessee Republican Senator Howard Baker, who died in 2014. Their marriage was the first between a man and a woman who had both served in the Senate. After leaving the Senate, Kassebaum Baker remained involved in public service, including roles on a bipartisan commission on campaign finance reform and a British commission in Africa. She accompanied her husband when he served as U.S. ambassador to Japan from 2001 to 2005.

In later years, Kassebaum Baker became critical of the increasing conservatism within the Republican Party. She endorsed Democratic candidates for statewide offices in Kansas and stated in 2021 that then-President Donald Trump should be impeached following the attack on the U.S. Capitol.