The 1972 United States Senate elections were held on November 7, with the 33 seats of Class 2 contested in regular elections. They coincided with the landslide re-election of Republican President Richard Nixon. Despite Nixon's landslide victory, Democrats increased their majority by two seats. The Democrats picked up open seats in Kentucky and South Dakota, and defeated four incumbent senators: Gordon Allott of Colorado, J. Caleb Boggs of Delaware, Jack Miller of Iowa, and Margaret Chase Smith of Maine. The Republicans picked up open seats in New Mexico, North Carolina, and Oklahoma, and defeated one incumbent, William B. Spong Jr. of Virginia. After the elections, Democrats held 56 seats, and Republicans held 42 seats, with 1 Conservative and 1 independent senator in the chamber as well. These were the first elections in which all citizens at least 18 years of age (instead of 21, and older) could vote, due to the 1971 passage of the 26th Amendment. As of , this is the last time in which a Republican won a Senate election in New Jersey. Joe Biden, the 46th president of the United States (2021–present) and 47th vice president (2009–2017), first won election to the United States Senate, defeating J. Caleb Boggs in the election in Delaware. Results summary Source: Gains, losses, and holds Retirements Three Republicans and three Democrats retired instead of seeking re-election. Defeats Four Republicans and three Democrats sought re-election but lost in the primary or general election. Change in composition Before the elections After the January 7, 1972, Vermont special election. Elections results Race summaries Special elections during the 92nd Congress In these special elections, the winner was seated during 1972 or before January 3, 1973; ordered by election date, then state. Elections leading to the next Congress In these general elections, the winners were elected for the term beginning January 3, 1973; ordered by state. All of the elections involved the Class 2 seats. Alabama Alaska Ted Stevens won re-election to a second term (his first full term) against Democrat Gene Guess. Arkansas Incumbent Democrat John Little McClellan was re-elected. Colorado Incumbent Republican Gordon Allott was defeated by Floyd K. Haskell. Delaware Incumbent Republican J. Caleb Boggs, running for a third term, faced off against future President Joe Biden, then a New Castle County Councilman. Though Boggs was expected to easily win a third term over the then-unknown Biden, it ended up being the