United States Senate election in Illinois, 1966

The 1966 United States Senate election in Illinois took place on November 8, 1966. Incumbent Democratic United States Senator Paul Douglas, seeking a fourth term in the United States Senate, faced off against Republican Charles H. Percy, a businessman and the 1964 Republican nominee for Governor of Illinois. A competitive election ensued, featuring campaign appearances by former Vice-President Richard M. Nixon on behalf of Percy. Ultimately, Percy ended up defeating Senator Douglas by a fairly wide margin, allowing him to win what would be the first of three terms in the Senate.