The 1960 United States Senate elections coincided with the election of John F. Kennedy as president on November 8, 1960. The 33 seats of Class 2 were contested in regular elections. A special election was also held on June 28, 1960, for a mid-term vacancy in North Dakota where Democrats flipped a seat to expand their majority to 66–34. As Majority Leader Lyndon Johnson was elected Vice President, Mike Mansfield became the new majority leader.

The 1962 United States Senate elections was an election for the United States Senate. Held on November 6, the 34 seats of Class 3 were contested in regular elections. Special elections were also held to fill vacancies. They occurred in the middle of President John F. Kennedy's term. His Democratic Party made a net gain of four seats from the Republicans, increasing their control of the Senate to 68–32. However, this was reduced to 67–33 between the election and the next Congress, as on November 18, 1962, Democrat Dennis Chávez, who was not up for election that year, died. He was replaced on November 30, 1962, by Republican appointee Edwin L. Mechem. Additionally, Democrat Strom Thurmond became a Republican in 1964, further reducing Democrats to 66–34. This was the first time since 1932 that Democrats gained seats in this class of Senators.