The 2018 United States elections were held on Tuesday, November 6, 2018. These midterm elections occurred during Incumbent Republican President Donald Trump's term. Although the Republican Party increased its majority in the Senate, unified Republican control of Congress and the White House was brought to an end when the Democratic Party won control of the House of Representatives in what was widely characterized as a "blue wave" election.

Democrats made a net gain of 41 seats in the United States House of Representatives, gaining a majority in the chamber and thereby ending the federal trifecta that the Republican Party had established in the 2016 elections. The Republican Party retained control of the United States Senate, making a net gain of two seats and defeating four Democratic incumbents in states that had voted for Trump in 2016. As a result of the 2018 elections, the 116th United States Congress became the first Congress since the 99th United States Congress (elected in 1984) in which the Democrats controlled the U.S. House of Representatives and the Republicans controlled the U.S. Senate. In state-level elections, Democrats picked up a net of seven governorships and several state legislative seats.

2018 United States elections

This was the first time since 1970 that one party gained Senate seats while losing House seats, which also occurred in 1914, 1962, and 2022. In the state elections, Democrats gained seven state governorships, control of approximately 350 state legislative seats, and control of six state legislative chambers.

2018 United States elections

The elections marked the highest voter turnout seen in midterm elections since 1914, at 49.4%. The elections saw several electoral firsts for women, racial minorities, and LGBT candidates, including the election of the first openly gay governor and the first openly bisexual U.S. senator. In various referendums, numerous states voted to expand Medicaid coverage, require voter identification, establish independent redistricting commissions, legalize marijuana, repeal felony disenfranchisement laws and enact other proposals. During the campaign, Democrats focused on health care, frequently attacking Republicans for supporting repeal of provisions of the Patient Protection and Affordable Care Act (also known as Obamacare), including protections for individuals with preexisting conditions. They also focused on tying many Republican incumbents and candidates to President Trump, who had low approval ratings at the time of the election. Republican messaging focused on immigration and the Tax Cuts and Jobs Act of 2017. There were allegations of attempted Russian interference in these elections as well as controversies regarding potential voter suppression and other alleged election irregularities.

2018 United States elections

Republican losses across the country are attributed to the party's efforts to repeal and replace the Affordable Care Act with the failed American Health Care Act of 2017 and widespread opposition to it amongst Americans, as well as liberal and suburban discontent with President Trump over his policies and temperament as president.

Issues, advertisements, and campaigning

In May 2018, President Trump began to emphasize his effort to overcome the traditional strength of the non-presidential party in midterm elections, with the "top priority for the White House [being to hold] the Republican majority in the Senate". He was already well into his own 2020 reelection campaign, having launched it on his inauguration day in January 2017. By early August, the president's midterm efforts had included rallies in Ohio, Pennsylvania, Florida, Montana and elsewhere "reprising the style and rhetoric of his 2016 campaign". He focused his message on the economy, his proposed border wall, the "trade war" with China, criticism of the media, and his proposal to create the space force, a new branch of the military devoted to operations in space. In late August 2018, the Huffington Post reported that Trump and his administration had been engaging in campaign activity on taxpayer-funded trips. According to the report, a top White House staffer identified 35 events by Cabinet and senior staff members "with or affecting House districts in August already". White House Deputy Press Secretary Lindsay Walters called the report "misleading".