The 1998 United States Senate elections were held on November 3 and seen as an even contest between the Republican Party and Democratic Party. While the Democrats had to defend more seats up for election, Republican attacks on the morality of President Bill Clinton failed to connect with voters and anticipated Republican gains did not materialize. The Republicans picked up open seats in Ohio and Kentucky and narrowly defeated Democratic incumbent Carol Moseley Braun (Illinois), but these were cancelled out by the Democrats' gain of an open seat in Indiana and defeats of Republican Senators Al D'Amato and Lauch Faircloth. The balance of the Senate remained unchanged at 55–45 in favor of the Republicans. With Democrats gaining five seats in the House of Representatives, this marked the first time since 1934 that the out-of-presidency party failed to gain congressional seats in a mid-term election, and the first time since 1822 that the party not in control of the White House failed to gain seats in the mid-term election of a President's second term. These are the last senate elections that resulted in no net change in the balance of power.
The 1990 United States Senate elections were held on Tuesday, November 6, 1990. The Democratic Party increased its majority with a net gain of one seat from the Republican Party. The election took place in the middle of President George H. W. Bush's term, and, as with most other midterm elections, the party not holding the presidency gained seats in Congress.
The 1988 United States Senate elections was an election for the United States Senate in which, in spite of the Republican victory by George H. W. Bush in the presidential election, the Democrats gained a net of one seat in the Senate. Seven seats changed parties, with four incumbents being defeated. The Democratic majority in the Senate increased by one from 54/46 to 55/45.
The 1986 United States Senate elections was an election for the United States Senate in the middle of Ronald Reagan's second presidential term. The Republicans had to defend an unusually large number of freshman Senate incumbents who had been elected on President Ronald Reagan's coattails in 1980. Democrats won a net of eight seats, defeating seven freshman incumbents and regaining control of the Senate for the first time since January 1981. The party not controlling the presidency gained seats, as usually occurs in mid-term elections.
The 1984 United States Senate elections coincided with the landslide re-election of President Ronald Reagan in the presidential election. In spite of the lopsided presidential race, Reagan's Republican Party suffered a net loss of two Senate seats to the Democrats, although it retained control of the Senate and gained seats in the House.
The 1982 United States Senate elections were held on November 2, 1982. They were elections for the United States Senate following Republican gains in 1980. A total of four seats changed hands between parties, and the lone independent, Senator Harry Byrd Jr., retired. Democrats made a net gain of one seat in the elections. A special election in 1983 was then held after the winner of Washington's 1982 election died at the beginning of the term.
The 1980 United States Senate elections coincided with Ronald Reagan's victory in the presidential election. Reagan's large margin of victory over incumbent Jimmy Carter pulled in many Democratic voters and gave a huge boost to Republican Senate candidates.
The 1978 United States Senate elections in the middle of Democratic President Jimmy Carter's term. Thirteen seats changed hands between parties. The Democrats at first lost a net of two seats to the Republicans, and then one more in a special election. Democrats nevertheless retained a 58-41 majority.
The 1976 United States Senate elections was an election for the United States Senate that coincided with Democratic Jimmy Carter's presidential election and the United States Bicentennial celebration. Although almost half of the seats decided in this election changed parties, Carter's narrow victory did not provide coattails for the Democrats, and the balance of the chamber remained the same.
The 2008 United States Senate elections were held November 4, 2008, with 35 of the 100 seats in the Senate being contested. Thirty-three seats were up for regular elections; the winners were eligible to serve six-year terms from January 3, 2009 to January 3, 2015, as members of Class 2. There were also two special elections, the winners of those seats would finish the terms that ended January 3, 2013.
The 1970 United States Senate elections was an election for the United States Senate, taking place in the middle of Richard Nixon's first term as President. The Democrats lost a net of three seats, while the Republicans and the Conservative Party of New York picked up one net seat each, and former Democrat Harry F. Byrd Jr. was re-elected as an independent.
The 1968 United States Senate elections were elections for the United States Senate which coincided with the presidential election. Although Richard Nixon won the presidential election narrowly, the Republicans picked up five net seats in the Senate. Republicans would gain another seat after the election when Alaska Republican Ted Stevens was appointed to replace Democrat Bob Bartlett.
The 1964 United States Senate elections 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 2019, this is the last time either party has had a two-thirds majority in the Senate, which would have hypothetically allowed the Senate Democrats to override a veto, convict and expel certain officials, or invoke cloture without any votes from Republicans. The Senate election coincided with Democratic gains in the House in the same year.
The 1958 United States Senate elections were elections for the United States Senate which occurred in the middle of President Dwight D. Eisenhower's second term. As is common in midterm elections, the party in the White House lost seats, but losses this year were more than usual, perhaps due to the high unemployment of the Recession of 1958. The Eisenhower Administration's position on right-to-work issues galvanized labor unions which supported Democrats. The launch of Sputnik may also have been a factor.
The 1956 United States Senate elections were elections for the United States Senate that coincided with the re-election of President Dwight D. Eisenhower. Although the Democrats gained two seats in regular elections, the Republicans gained back two seats in special elections, leaving the party balance of the chamber remained unchanged.
The 1954 United States Senate elections was a midterm election in the first term of Dwight D. Eisenhower's presidency. 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 support of an Independent who caucused with them.
The 1946 United States Senate elections were held November 5, 1946, in the middle of Democratic President Harry S. Truman's first term.
The United States Senate elections of 1940 coincided with the election of Franklin D. Roosevelt to his third term as President.
The United States Senate elections of 1928 were elections that coincided with the presidential election of Republican Herbert Hoover. The strong economy helped the Republicans to gain seven seats from the Democrats.
The 1972 United States Senate election in Maine was held on November 7, 1972. Incumbent Republican U.S. Senator Margaret Chase Smith ran for re-election to a fifth term, but was defeated by Democrat William Hathaway. As of 2019, this is the last time the Democrats have won the Class 2 Senate Seat from Maine.
