Presidential elections garner the most attention from the media and political elites. Yet they are not the only important elections. The even-numbered years between presidential years, like 2014 and 2018, are reserved for congressional elections—sometimes referred to as midterm elections because they are in the middle of the president’s term. Midterm elections are held because all members of the House of Representatives and one-third of the senators come up for reelection every two years.

During a presidential election year, members of Congress often experience the coattail effect, which gives members of a popular presidential candidate’s party an increase in popularity and raises their odds of retaining office. During a midterm election year, however, the president’s party often is blamed for the president’s actions or inaction. Representatives and senators from the sitting president’s party are more likely to lose their seats during a midterm election year. Many recent congressional realignments, in which the House or Senate changed from Democratic to Republican control, occurred because of this reverse-coattail effect during midterm elections. The most recent example is the 2010 election, in which control of the House returned to the Republican Party after two years of a Democratic presidency.