She earned a bachelor’s degree in history from Wells College in Aurora, N.Y., in 1960 and graduated from the University of Pennsylvania Law School.
A former Kennedy Democrat, Mrs. Whittlesey was elected to the Pennsylvania Legislature as a Republican from Delaware County in 1972. Four years later, at the national convention, she bolted party regulars who were behind President Gerald R. Ford to support Reagan in his ultimately unsuccessful bid for the nomination. (More recently, she was an early supporter of Donald J. Trump.)
“I remember someone once told me how I was described during this period,” she said in a 1989 interview for an oral history project. “They said, ‘She looks like a woman, she thinks like a man, and she fights like a dog.’ ”
Mrs. Whittlesey emerged from a largely blue-collar upbringing to win full scholarships to college and law school and become an accomplished classical pianist and gardening enthusiast. The American Rose Society named a tea rose variety after her.
She also endured her share of personal tragedy. Both her husband, Roger Weaver Whittlesey, and their elder son, Henry, struggled with depression. Both committed suicide, Mr. Whittlesey in 1974 and Henry in 2012. Mrs. Whittlesey lost her right eye to cancer in 1994 and part of a lung in 2001.
In addition to their son William, Mrs. Whittlesey is survived by a daughter, Amy Whittlesey O’Neill; 10 grandchildren; and a brother, Thomas Martin Ryan.
“While some might criticize her persistence as toughness, Faith portrayed this strength of purpose as an essential ingredient of her political survival,” Thomas J. Carty wrote in “Backwards, in High Heels: Faith Whittlesey, Ronald Reagan’s Madam Ambassador in Switzerland and the West Wing” (2012).
“A woman is supposed to be submissive,” she once said. “I won’t play that role. I wouldn’t be where I am today if I did.”