Slade Gorton, a patrician and cerebral politician from Washington state who served in the Republican leadership during almost 20 years in the U.S. Senate, died Aug. 19 in Seattle. He was 92.

The death was confirmed by his former chief of staff, J. Vander Stoep. The cause and other details were not immediately disclosed.

Mr. Gorton was the Chicago-born scion of a New England family that started a well-known company selling frozen fish. After settling in Seattle in 1956 to practice law, he went on to have a 40-year career as an old-line, centrist Republican. He served in the state legislature and as state attorney general and had three nonconsecutive terms as a U.S. senator.

As Washington’s attorney general in the 1970s, Mr. Gorton was known for his aggressive consumer-protection battles. In 1980, he defeated longtime Democratic Sen. Warren Magnuson, emphasizing his relative youth, in contrast to the aging incumbent, by running to the state capital of Olympia to file his candidacy papers.

He was one of the Republicans swept into office on the coattails of Ronald Reagan’s landslide presidential victory, marking the first time the GOP had controlled the Senate in more than a quarter century.

Mr. Gorton had a seat on the influential Budget Committee and worked on Social Security and the budget. He seemed set for a long career in the Senate but was narrowly defeated in his 1986 reelection bid by Democrat Brock Adams.

Two years later, Mr. Gorton ran to fill an open Senate seat, defeating Democrat Mike Lowry with 51 percent of the vote. He easily won reelection in 1994 and became part of the GOP leadership under Majority Leader Trent Lott (R-Miss.), who praised Mr. Gorton’s “wise counsel.”

Mr. Gorton twice saved professional baseball in Seattle, suing Major League Baseball in the 1970s to force it to bring a team to the city and arranging a deal to have Nintendo’s owner and local investors buy the Mariners to keep them in town in 1991.

Democratic Sen. Patty Murray (Wash.), who overlapped with Mr. Gorton in the Senate, said they didn’t always agree, but still worked together to strengthen clean-up efforts at the Hanford Nuclear Reservation in Washington state, toughen pipeline safety standards and expand health care for children.

Murray said Mr. Gorton “anchored his leadership in honesty and honor,” such as when he bucked his party to support the National Endowment for the Arts, collaborated with Democrats on the conduct of President Bill Clinton’s impeachment trial, and supported the impeachment of President Trump.

Mr. Gorton also supported the Equal Rights Amendment for women and the use of federal funds to pay for abortions for poor women,

“Throughout his career in both Washingtons, Slade defied convenient labels and stood on principle — we need more leaders in our country like Slade,” Murray said in an emailed statement.

By 2000, the 72-year-old Mr. Gorton was looking over his shoulder at a challenger 30 years his junior, Democrat Maria Cantwell. In an election in which nearly 2.4 million votes were cast, Cantwell prevailed by about 2,000 votes.

Thomas Slade Gorton III was born Jan. 8, 1928, in Chicago and grew up in the Chicago suburbs. He served in the Army near the end of World War II, graduated Phi Beta Kappa from Dartmouth College in 1950 and received a law degree from Columbia University in 1953.

He then served in the Air Force before moving to Seattle in 1956, with the notion of breaking into Republican politics. Two years later, he was elected to the state legislature, where he served for 10 years. He later served three terms as state attorney general. In the 1970s, he was among the first Republican officeholders to call on President Richard M. Nixon to resign for his role in the Watergate scandal.

After leaving the U.S. Senate, he served on the 9/11 Commission and on the National Commission on Federal Election Reform, as well as numerous civic boards and campaigns.

His wife of 55 years, the former Sally Clark, died in 2013. Survivors include three children and several grandchildren.