The 1978 United States Senate elections were held on November 7, in the middle of Democratic President Jimmy Carter's term. The 33 seats of Class 2 were contested in regular elections. Special elections were also held to fill vacancies.
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.
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.
The 1954 United States Senate elections was a midterm election in the first term of Dwight D. Eisenhower's presidency. The 32 Senate seats of Class 2 were contested in regular elections, and six special elections were held to fill vacancies. Eisenhower's Republican party lost a net of two seats to the Democratic opposition. This small change was just enough to give Democrats control of the chamber with the help of the Independent who at the start of this Congress in January 1955 agreed to caucus with them; he later officially joined the party in April 1955.
The 1952 United States Senate elections was an election for the United States Senate which coincided with the election of Dwight D. Eisenhower to the presidency by a large margin. The 32 Senate seats of Class 1 were contested in regular elections, and three special elections were held to fill vacancies. The Republicans took control of the Senate by managing to make a net gain of two seats. However, Wayne Morse (R-OR) became an independent forcing Republicans to rely on Vice President Richard Nixon's tie-breaking vote, although Republicans maintained a 48–47–1 plurality. Wayne Morse would caucus with the Republicans at the start of Congress’ second session on January 6, 1954 to allow the GOP to remain in control of the Senate. This was the third time, as well as second consecutive, in which a sitting Senate leader lost his seat.
The 1948 United States Senate elections were held concurrently with the election of Democratic President Harry S. Truman for a full term. The 32 seats of Class 2 were contested in regular elections, and one special election was held to fill a vacancy. Truman campaigned against an "obstructionist" Congress that had blocked many of his initiatives, and additionally, the U.S. economy recovered from the postwar recession of 1946–1947 by election day. Thus, Truman was rewarded with a Democratic gain of nine seats in the Senate, enough to give them control of the chamber. This was the last time until 2020 that Democrats flipped a chamber of Congress in a presidential election cycle.
The 1946 United States Senate elections were held November 5, 1946, in the middle of Democratic President Harry S. Truman's first term after Roosevelt's passing. The 32 seats of Class 1 were contested in regular elections, and four special elections were held to fill vacancies. The Republicans took control of the Senate by picking up twelve seats, mostly from the Democrats. This was the first time since 1932 that the Republicans had held the Senate, recovering from a low of 16 seats following the 1936 Senate elections.
The 1944 United States Senate elections coincided with the re-election of Franklin D. Roosevelt to his fourth term as president. The 32 seats of Class 3 were contested in regular elections, and three special elections were held to fill vacancies.
The 1942 United States Senate elections were held November 3, 1942, midway through Franklin D. Roosevelt's third term as president. The 32 seats of Class 2 were contested in regular elections, and two special elections were held to fill vacancies.
The 1938 United States Senate elections occurred in the middle of Franklin D. Roosevelt's second term. The 32 seats of Class 3 were contested in regular elections, and special elections were held to fill vacancies. The Republicans gained eight seats from the Democrats, though this occurred after multiple Democratic gains since the 1932 election, leading to the Democrats retaining a commanding lead over the Republicans with more than two-thirds of the legislative chamber.
The 1936 United States Senate elections coincided with the reelection of President Franklin D. Roosevelt. The 32 seats of Class 2 were contested in regular elections, and special elections were held to fill vacancies. The Great Depression continued and voters backed progressive candidates favoring Roosevelt's New Deal in races across the country. The Democrats gained 5 net seats during the election, and in combination with Democratic and Farmer–Labor interim appointments and the defection of George W. Norris from the Republican Party to become independent, the Republicans were reduced to 16 seats. Democrats gained a further two seats due to mid-term vacancies. The Democrats' 77 seats and their 62-seat majority remain their largest in history.
The 1934 United States Senate elections were held in the middle of Democratic President Franklin D. Roosevelt's first term. The 32 seats of Class 1 were contested in regular elections, and special elections were held to fill vacancies. During the Great Depression, voters strongly backed Roosevelt's New Deal and his allies in the Senate, with Democrats picking up a net of nine seats, giving them a supermajority. Republicans later lost three more seats due to mid-term vacancies ; however, a Democrat in Iowa died and the seat remained vacant until the next election. The Democrats entered the next election with a 70-22-2-1 majority.
The 1928 United States Senate elections were elections that coincided with the presidential election of Republican Herbert Hoover. The 32 seats of Class 1 were contested in regular elections, and special elections were held to fill vacancies. The strong economy helped the Republicans to gain seven seats from the Democrats.
The 1926 United States Senate elections were elections for the United States Senate that occurred in the middle of Republican President Calvin Coolidge's second term. The 32 seats of Class 3 were contested in regular elections, and special elections were held to fill vacancies. The Republican majority was reduced by seven seats.
The 1922 United States Senate elections were elections that occurred in the middle of Republican President Warren G. Harding's term. The 32 seats of Class 1 were contested in regular elections, and special elections were held to fill vacancies. With the Republicans divided between conservative and progressive factions, the Democrats gained six net seats from the Republicans while the Farmer–Labor party gained one. The Republicans retained their Senate majority.
The 1920 United States Senate elections were elections for the United States Senate that coincided with the presidential election of Warren G. Harding. The 32 seats of Class 3 were contested in regular elections, and special elections were held to fill vacancies. Democrat Woodrow Wilson's unpopularity allowed Republicans to win races across the country, winning ten seats from the Democrats and providing them with an overwhelming 59-to-37 majority. The Republican landslide was so vast that Democrats lost over half of the contested seats this year and failed to win a single race outside the South. In fact, this is the most recent occasion where every race decided by under 10 points all voted for the same party, showcasing the sheer strength of Republicans' performance in this election.
The 1918 United States Senate elections were held throughout 1918, the midpoint of Woodrow Wilson's second term as president. This was the first election since the ratification of the 17th Amendment that all 32 Class 2 senators were subject to direct or popular election, making them the final class under the old system of being selected by state legislatures. Special elections were also held to fill vacancies.
The 1912–13 United States Senate elections were held on various dates in various states. They were the last U.S. Senate elections before the ratification of the Seventeenth Amendment in 1913, establishing direct elections for all Senate seats. Senators had been primarily chosen by state legislatures. Senators were elected over a wide range of time throughout 1912 and 1913, and a seat may have been filled months late or remained vacant due to legislative deadlock. Some states elected their senators directly even before passage of Seventeenth Amendment. Oregon pioneered direct election and experimented with different measures over several years until it succeeded in 1907. Soon after, Nebraska followed suit and laid the foundation for other states to adopt measures reflecting the people's will. By 1912, as many as 29 states elected senators either as nominees of their party's primary or in conjunction with a general election.
Berkeley Lloyd Bunker was an American businessman and politician who served as both an appointed United States senator and one-term member of the U.S. House of Representatives from Nevada in the mid-20th century.
The following table indicates the party of elected officials in the U.S. state of Maine:
