About 210 million registered voters in the United States will cast their ballots on November 3 in elections that could reshape the balance of power in Washington and determine how much influence President Donald Trump has during the final two years of his term.
Although Trump is not on the ballot, control of the US Congress is. The legislature, comprising the House of Representatives and the Senate, is responsible for passing laws and approving federal spending.
Republicans currently control both chambers. If Democrats win either, they could block legislation, scrutinise the Trump administration and make it harder for the president to advance his domestic agenda.
The midterm elections, held halfway through a president’s four-year term, are also widely viewed as a referendum on the incumbent’s performance.
Here is a look at how the elections work, the key contests and what the outcome could mean for both parties.
What Happens in the US Midterm Elections?
Voters will decide the composition of the House of Representatives and part of the Senate.
All 435 seats in the House are being contested, along with 35 of the Senate’s 100 seats. The Senate contests include special elections in Florida and Ohio to fill the seats vacated by Marco Rubio, now US secretary of state, and JD Vance, now vice-president.
Voters in 36 states will also elect governors. State legislators and local officials are among those contesting elections.
Members of the House represent individual congressional districts and serve two-year terms. Senators represent their entire state and serve six-year terms.
What is at Stake in the House and Senate?
Republicans currently hold majorities in both chambers. Democrats need to gain three seats in the House and four in the Senate to take control.
A Democratic victory in either chamber would give the party greater power to block legislation and launch investigations into the Trump administration.
A 50-50 split in the Senate would leave Republicans in control, as Vice-President Vance can cast tie-breaking votes.
How Do House Elections Work?
The House of Representatives is the lower chamber of Congress. Its 435 members each represent a congressional district and serve two-year terms, meaning every seat is contested every two years.
The number of seats allocated to each state is based on its population, as determined by the US Census, which is conducted every 10 years. California, the most populous state, has 52 seats, while states including Wyoming and Vermont have one each.
A party needs 218 seats to secure a majority.
Republicans currently hold 218 seats, compared with 214 for Democrats. One independent sits with Republicans, while two seats are vacant, one last held by each party.
The new House will be sworn in on January 3, 2027.
Which House Races Should Be Watched?
A handful of closely contested districts could determine which party controls the chamber.
Todd Belt, a professor of political management at George Washington University, estimates that about 35 House races could decide the majority. He predicts Democrats could gain around 15 seats, despite Republican redistricting that he says has given the party an advantage in nine additional districts.
Voters generally tend to support candidates from the same party across different races, Belt said, meaning the national political climate could also affect contests further down the ballot.
How Do Senate Elections Work?
The Senate is the upper chamber of Congress. It has 100 members, with each of the 50 states electing two senators regardless of population.
Senators serve six-year terms, with roughly one-third of the seats contested every two years.
This year, 33 seats are being contested in regular elections, alongside special elections in Florida and Ohio. The two special contests will fill the remaining years of terms previously held by Rubio and Vance.
Of the 35 seats at stake, Republicans currently hold 22 and Democrats hold 13.
Republicans have 53 senators, while Democrats have 45. Two independents sit with the Democrats, giving the party’s bloc 47 seats.
Democrats need a net gain of four seats to reach 51 and take control. Republicans can retain the chamber with 50 seats because the vice-president can break a tie.
The new Senate will also be sworn in on January 3, 2027.
Which Senate Races Are Key?
Democrats must hold all 13 seats they are defending and win Republican-held seats if they are to secure a majority.
In Georgia, Democratic Senator Jon Ossoff is facing Republican Mike Collins. Michigan’s open seat is being contested by Democrat Abdul El-Sayed and Republican Mike Rogers, while Democrat Chris Pappas is facing Republican John Sununu in New Hampshire.
Other opportunities for Democrats include Maine, where Republican Senator Susan Collins is facing Democrat Troy Jackson, and North Carolina, where Democrat Roy Cooper is competing against Republican Michael Whatley for an open seat.
Ohio, Alaska and Iowa are also competitive. Texas and Kansas have attracted growing attention as Democrats look for additional routes to a Senate majority.
Although the Senate presents a more difficult path for Democrats than the House, election analysts say the growing number of competitive races has improved their chances.
Who is Voting in the Midterms?
About 210 million Americans are registered to vote, representing nearly eight in 10 US residents aged 18 and above, according to USAFacts, a non-partisan organisation that compiles government data.
California has the highest number of registered voters, at 23.2 million, followed by Texas with 17.4 million and Florida with 13.6 million. Together, the three states account for about 26% of registered voters.
Wyoming has the fewest registered voters, at 278,468, followed by Vermont with 459,455 and Alaska with 603,310.
What Happens if Republicans Lose the House?
A Democratic-controlled House could block Republican legislation and use its committees to investigate the Trump administration.
The House also has the power to impeach a president. Trump has already been impeached twice.
Control of the chamber would give Democrats significant influence over federal spending. Every funding bill must be approved by both the House and the Senate, meaning a Republican-controlled Senate could not pass legislation on its own.
Belt expects a Democratic House to lead to further confrontations over federal spending, including the 12 annual bills required to fund government agencies. Disagreements could increase the risk of government shutdowns, when funding lapses and many federal services are disrupted. He also suggested Trump could focus more heavily on foreign policy if Democrats block his domestic agenda.
What Happens if Republicans Lose the Senate?
A Democratic-controlled Senate could block legislation and reject presidential nominees, including federal judges, Supreme Court justices, cabinet officials and ambassadors.
The outcome could have consequences well beyond Trump’s remaining time in office. Federal judges serve for life, allowing their decisions to shape the country’s legal system for decades.
The Senate also conducts the trial if the House impeaches a president. Removing a president from office requires a two-thirds majority in the Senate, a threshold neither party is expected to reach.
Would Democrats Have Full Control If They Win Both Chambers?
No. Even if Democrats take control of both the House and Senate, Trump would remain president and retain the power to veto legislation.
Overriding a presidential veto requires a two-thirds majority in both chambers. Senate rules also generally require 60 votes to end debate on most legislation, although some budget bills can pass with a simple majority. A narrow majority, therefore, would not guarantee that Democrats could pass their entire legislative programme.
A Democratic-controlled House could begin impeachment proceedings against Trump, but removing him from office would still require a two-thirds majority in the Senate.
Belt considers another impeachment unlikely. “There will definitely be investigations,” he told Al Jazeera. But he added: “There will not likely be another impeachment because Democrats tried that twice and Republicans rallied behind Trump.”
When Will the Results Be Known?
The first results are expected after polling stations begin closing at 6pm Eastern time on November 3.
However, close contests could take days to resolve. Election-night figures are preliminary, and final results may take days or, in some cases, weeks as officials count mail-in, provisional and other outstanding ballots before certifying the results.
The counting process varies by state. In some places, it could take a week or longer, Belt said.
Georgia could see a further vote in the Senate race if no candidate wins a majority. In that case, a run-off election would be held on December 1.
