About this election
The 2018 United States Senate elections were held on 6 November 2018, at the midpoint of Donald Trump's first term. Although Democrats won a sweeping victory in the concurrent House elections, the Senate moved the other way: Republicans made a net gain of two seats, expanding their majority to 53 against 45 Democrats and two independents who caucus with them, an effective 53–47 split. The contrast between the two chambers made 2018 one of the rare midterms in which the president's party lost the House but strengthened its hold on the Senate.
Thirty-five seats were contested — the Class 1 senators plus two special elections, in Minnesota and Mississippi, to fill mid-term vacancies. As always, each seat is decided by statewide vote for a six-year term, with the chamber's two-per-state composition giving smaller, more rural states outsized weight. The map shows the winning party in each state that held a Senate race in 2018, including the two independents (Angus King of Maine and Bernie Sanders of Vermont) who were both re-elected.
The arithmetic of the cycle was deeply unfavourable to Democrats, who were defending 26 of the 35 seats, including ten in states Trump had carried in 2016. That exposure, even amid a strong national environment for the party, allowed Republicans to net gains despite losing ground almost everywhere else in the country.
Republicans defeated four Democratic incumbents in Trump-leaning states: Heidi Heitkamp in North Dakota, Joe Donnelly in Indiana, Claire McCaskill in Missouri, and Bill Nelson in Florida, the last by a margin of about ten thousand votes after a recount. Democrats, in turn, flipped two seats in the Sun Belt: Kyrsten Sinema won an open seat in Arizona, and Jacky Rosen unseated Dean Heller in Nevada — the only Republican senator up that year in a state Hillary Clinton had carried. The Texas race, in which Beto O'Rourke came within three points of Ted Cruz, drew national attention and record fundraising even though Cruz held on.
The expanded Republican majority insulated the chamber from the Democratic House and ensured continued control of confirmations through the second half of Trump's term. It allowed Republicans to keep approving federal judges at a rapid pace and shaped the balance of power for the 2020 cycle, when the larger number of exposed Republican seats would help Democrats fight the chamber back to a tie.
Federal Election Commission (FEC), official 2018 Senate general-election results — fec.gov.
Compiled and reviewed by Bartłomiej Paruzel, Election Data Analyst, from official results. See our data methodology.