Mark Dayton, Democrat US Senator from Minnesota (2001-). He was born January 26, 1947 in Minneapolis, Minnesota. Dayton graduated cum laude Yale University, 1969. He was an unsuccessful candidate for the United States Senate in 1982. Mark Dayton served as a legislative assistant to Senator Walter Mondale. He was Minnesota state auditor, 1991-1995 and elected to the United States Senate in 2000. He defeated incumbent Rod Grams.