Humphrey was appointed as a member of the Democratic-Farmer-Labor Party by Rudy Perpich, the Governor of Minnesota, to the Senate vacancy caused by her husband's death. She had served from January 25, 1978 to November 7, 1978 in the 95th United States Congress. She was the first spouse of a former Vice President to serve in Congress, as well as the first woman to represent Minnesota in the U.S. Senate. She was not a candidate for the special election for the remaining term. "It was the most challenging thing I've done in my whole life," she said. Twenty-eight years later, Amy Klobuchar, a fellow Democratic-Farmer-Labor, would become the first woman to be elected to the United States Senate from Minnesota.