US midterm elections: Republicans and Democrats battle for control of Congress

US voters will decide in the midterm elections whether Republicans retain control of Congress or Democrats rise up to stymie President Donald Trump's agenda.

Donald Trump will still be US president on the morning of 4 November. But he could be facing a very different political landscape, depending on the results of the midterm elections held the previous day.

As the name implies, midterm elections fall nearly halfway through a president's term. They are often seen as a telling referendum on the sitting president's performance, something Trump is actively encouraging by telling voters to 'pretend I'm on the ballot'.

The US Congress has two chambers: the House of Representatives and the Senate. Both must approve federal legislation before it can become law, and both play important roles in overseeing the executive branch.

The House is elected every two years, meaning all 435 voting seats are contested at every congressional election. Republicans are defending a narrow majority, with Democrats needing a net gain of four seats to take control.

Thirty-five seats are being contested in the Senate: 33 in regular elections, along with two special elections in Florida and Ohio to fill the remainder of terms vacated early. Republicans currently hold 53 seats, against 47 held by Democrats and independents who caucus with them. Democrats need to gain four seats to secure a majority.

Alongside Congress, 39 governorships are at stake — voters will choose governors in 36 states and three US territories. Thousands of state legislative seats, local offices, judicial contests and ballot measures on issues including taxes, abortion rights and voting rules are also on the ballot.

Midterm elections have a long history of punishing the occupant of the White House. The president's party has lost House seats in 18 of the past 20 midterm elections, a 90% rate of loss stretching back to 1946.

The pattern is not inevitable. George W Bush's Republicans gained seats in the 2002 midterms, following the September 11 attacks. But Barack Obama's Democrats suffered a 'shellacking' in 2010, and Trump's Republicans lost the House in 2018.

The RealClearPolitics average of national generic polls showed Democrats leading Republicans by 8.2 points in early October. But political polarisation and years of redistricting have reduced the number of genuinely competitive House districts; the Reuters news agency has estimated that only about 40 to 50 House races are truly competitive. Trump has been forced to hold campaign rallies in what should be safe Republican states.

Several Senate contests have emerged as key battlegrounds. In Michigan, progressive Abdul El-Sayed is seeking to hold an open seat for the Democrats after incumbent senator Gary Peters decided not to seek re-election. In Georgia, Democratic senator Jon Ossoff enjoys a healthy poll lead over Republican challenger Mike Collins.

In Maine, a state won by Democrat Kamala Harris in 2024, Republican senator Susan Collins is defending her seat against Democrat Troy Jackson. Ohio offers another major test, with Democrat Sherrod Brown seeking to return to the Senate against Republican Jon Husted.

Texas has become especially closely watched. Democrat James Talarico is taking on Republican Ken Paxton, the state's attorney general. Republicans have spent about $210m to help the scandal-plagued Paxton. No Democrat has won a statewide election in Texas since 1994, and Trump won Texas by nearly 14 points.