Robert Knous by just under eight percentage points. He would wind up winning re-election in 1966 before retiring in 1973, replaced by Democrat Floyd Haskell. Delaware J. Allen Frear ran for re-election to a third term, but he was defeated by Republican governor J. Caleb Boggs by a narrow 1% margin. Boggs would be re-elected in 1966, but he would lose re-election to a third term in 1972 to future U.S. President Joe Biden. Georgia Incumbent Richard B. Russell Jr. was re-elected to a sixth term in office, running unopposed in the tantamount Democratic primary and facing nominal opposition in the deeply-Democratic Georgia. Idaho Henry Dworshak ran for re-election to a third term, defeating R.F. McLaughlin by just under five percentage points. Illinois Incumbent Paul H. Douglas successfully ran for re-election to a third term, defeating Republican Samuel Witwer. Iowa Incumbent Republican Thomas Martin decided to retire, leaving this seat open. Republican Jack Miller won the open seat, defeating Democrat Herschel C. Loveless and riding the coattails of Richard Nixon's victory in the state. Kansas Incumbent Andrew Schoeppel ran for re-election to a third term, defeating Frank Theis. He would die before his term expired, and he was replaced by James B. Pearson. Kentucky Incumbent John Sherman Cooper ran for re-election, defeating Keen Johnson by nearly 20%. This was the first time Cooper had won an election to a full Senate term, though he had previously served two partial terms. Louisiana Incumbent Democrat Allen J. Ellender ran for re-election, having served since his election in 1936. In the deeply Democratic state of Louisiana, he was easily re-elected to another term. Maine Incumbent Republican Margaret Chase Smith, the first woman to serve in both houses of Congress, was overwhelmingly re-elected to a third term, defeating Lucia Cormier. This was the first election in which a woman was nominated by both major parties for the office of U.S. Senate, meaning a woman was going to be elected regardless of who won. Massachusetts Republican incumbent Leverett Saltonstall was re-elected to another term after being elected in 1944 in a special election. He defeated Democrat Thomas O'Connor Jr. Michigan Democrat Patrick V. McNamara was narrowly re-elected against Republican Alvin Bentley, having served one full term prior. Minnesota Democrat Hubert Humphrey, who would later become vice president, was re-elected over Republican challenger P. Kenneth Peterson. He had served since 1949. Mississippi Incumbent James Eastland, who