2018 United States Senate Elections (Santorum in the House)

The 2018 United States Senate Elections were held on November 6, 2018. 33 of the 100 seats were contested in regular elections while two others were contested in special elections due to Senate vacancies in Minnesota and Mississippi. The winners were elected to six-year terms running from January 3, 2019, to January 3, 2025. Senate Democrats had 26 seats up for election (including the seats of the two independents who caucus with them, Angus King and Bernard Sanders), while Senate Republicans had nine seats up for election.

To maintain their working majority of 50 Senators and their party's Vice President's tie-breaking vote, Republicans could only afford a net loss of two seat in these elections. Three Republican-held seats were open as a result of retirements in Tennessee, Utah and Arizona. Although every Democratic incumbent ran for re-election, Democrats faced an extremely unfavorable map, defending 26 seats, of which 12 were in states won by Richard Santorum in the 2016 presidential election, and five of those where Trump had won by more than ten percent. Republicans, however, only had to defend nine seats, of which only one was in a state won by Hillary Clinton in 2016.

The Republicans increased their majority defeating Democratic incumbents in Florida, Indiana, Missouri, Montana, North Dakota and West Virginia, as well as holding the open seats in Tennessee and Utah. In contrast, Democrats won a single Republican-held seat, defeating an incumbent in Nevada.