Sally Atwater, a special-education teacher and Republican political activist married to GOP strategist Lee Atwater, died March 9 at her home in Washington. She was 69.

The cause was lung cancer, said her daughter Sally Atwater McLeod. Ms. Atwater and her doctor had won approval for the use of experimental drug therapy to treat the illness, which she credited with adding three years to her life.

Described by Republican strategist Luke Byars as a political “force” in her home state of South Carolina, Ms. Atwater was associated for some primarily with her late husband. Lee Atwater served as an adviser to Presidents Ronald Reagan and George H.W. Bush, chaired the Republican National Committee and was known for his aggressive political tactics, including “dirty tricks” operations against Democrats.

Working at the Education Department in the 1980s, Ms. Atwater remained in Washington after her husband died of a brain tumor in 1991, at 40. Under President George W. Bush, she directed the President’s Committee for People With Intellectual Disabilities.

She later returned to South Carolina, where she taught special education classes and became active in Republican circles. In 2014, she finished second in an eight-way GOP primary for the state’s top public education post, forcing fellow contender Molly Spearman — who topped her by less than half a percent — into a runoff.

Ms. Atwater was endorsed by George H.W. Bush and his wife, Barbara, but lost the runoff by double digits. She later served as an at-large delegate to the 2016 Republican National Convention from South Carolina, initially campaigning for former Florida governor Jeb Bush before supporting Donald Trump’s candidacy.

As president, Trump appointed her to the Commission on Presidential Scholars, which recognizes distinguished high school students.

Sally Wilson Dunbar was born in Union, S.C., on April 29, 1951. She graduated from Winthrop College, now a university, and remained at the school to earn a master’s degree in special education.

While interning for Sen. Strom Thurmond (R-S.C.) in Washington, she met Atwater, the executive director of the College Republicans. The young political operative borrowed a boat from George H.W. Bush, then the chairman of the RNC, to take her out on the Potomac River for their first date. They married in 1978.

Survivors include three daughters, Sara Lee Atwater of Brussels, Ashley Vazana of Springfield, Va., and Sally Atwater McLeod of Washington; a brother; and three grandchildren.