An election was held on November 6, 2018 to elect 10 of the 21 members to Delaware's State Senate. The election coincided with the elections for other offices, including U.S. Senate, U.S. House of Representatives and State House. The primary election was held on September 6, 2018. Delaware Republicans needed to have a net gain of 1 seat to flip the chamber from the Democrats, however, Democrats increased their majority in the Senate by gaining 1 seat (winning 12 seats compared to 9 seats for the Republicans).