1964 United States Senate elections
The 1964 United States Senate elections were held on November 3. The 33 seats of Class 1 were contested in regular elections. Special elections were also held to fill vacancies. They coincided with the election of President Lyndon B. Johnson by an overwhelming majority, to a full term. His Democratic Party picked up a net two seats from the Republicans. As of 2023, this was the last time either party has had a two-thirds majority in the Senate, which allowed the Senate Democrats to override a veto, propose constitutional amendments, or convict and expel certain officials without any votes from Senate Republicans. However, internal divisions would have prevented the Democrats from having done so. The Senate election cycle coincided with Democratic gains in the House in the same year.
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35 of the 100 seats in the United States Senate 51 seats needed for a majority | |||||||||||||||||||||||||||||||||||||
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Results of the elections: Democratic gain Democratic hold Republican gain Republican hold No election Rectangular inset (Tennessee): both seats up for election | |||||||||||||||||||||||||||||||||||||
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In a close race in Nevada, Democratic incumbent Howard Cannon won re-election over Republican Lieutenant Governor Paul Laxalt by fewer than 100 votes. Laxalt joined Cannon in the Senate when he won Nevada's other seat in 1974. Patrick V. McNamara (D–Michigan) later died on April 30, 1966, and was replaced on May 11, 1966, by appointee Robert P. Griffin (R), reducing Democrats' majority to 67–33.
Notably, of the 35 seats up for election this year, 26 were held by Democrats, who managed to retain 25 of them. A party defending two-thirds of the seats up for election would not make net gains in the Senate again until 2012. Coincidentally, it would be the same Senate class, class 1. This is the earliest round of Senate elections in which a first-elected member is still alive (Fred Harris, D-OK).