Your fast guide to the US midterms and how they work

On November 3, Americans will head to the polls in midterm elections that could have big ramifications for the second half of Donald Trump’s presidency.

All seats in the US House of Representatives and a third of those in the Senate come up for grabs.

The results will determine whether the Democrats can neuter Trump’s agenda or if he will maintain his grip on America until the presidential election in November 2028.

The elections, which are on track to be America’s most expensive ever, are being fought on everything from the cost of living to the war on Iran, artificial intelligence and data centres, abortion rights, the immigration crackdown, and, of course, the president himself.

How do the midterms work?

The US midterms take place on the Tuesday after the first Monday of November, as stipulated in a law passed 181 years ago. They are held midway between presidential elections to determine the makeup of Congress, which comprises both the House of Representatives (which has two-year terms) and the Senate (which has six-year terms).

The Trump administration narrowly controls Congress. In the House of Representatives, the Republicans hold a five-seat majority, with 219 seats (including an independent who votes Republican) against the Democrats’ 214. In the Senate, Republicans have 53 seats versus the Democrats’ 47 (including two independents who vote Democrat).

Come November, all 435 seats in the House (the lower chamber of Congress) are up for re-election. In addition, a total of 35 Senate seats (the upper chamber) are up for grabs, which comprises a third of all Senate seats, plus two seats vacated by prominent Republicans JD Vance (who became vice president) and Marco Rubio (who became secretary of state). In addition to Congress, 36 out of 50 states will have gubernatorial elections on the same day.

Who’s expected to win?

To take control of the House, the Democrats need to pick up at least six more seats (218 seats in total); in the Senate, they need to win a net four seats (51).

Polling shows Democrats are on track to win the House easily, and possibly the Senate.

That’s largely because the unpopular war on Iran and high inflation have pushed Trump’s popularity to the lowest point in his political career. Having started his second term with an approval rating of 47 per cent, the latest Reuters/Ipsos poll found Trump’s approval rating had slumped to 32 per cent. The same poll found 43 per cent of registered voters planned to vote for the Democrats in these midterms, and 35 per cent for the Republicans – the biggest lead for the Democrats this year.

Winning control of both houses would frustrate Trump’s agenda for the final two years of his presidency, plus revive the Democrats ahead of the 2028 presidential campaign. “A win is now measured based on how many seats Democrats pick up rather than getting to a balance or status quo,” says Cory Alpert, who worked in the Biden-Harris administration.

Alpert expects young Democrat senator Jon Ossoff to beat Republican Mike Collins in the battleground state of Georgia, and Democratic nominee Roy Cooper to defeat Michael Whatley in North Carolina.

“I think races in Texas, Ohio, Alaska, and Michigan are all toss-ups, which in this environment probably favour the Democrat in the race. Florida, South Carolina, Kansas, Iowa, and Nebraska are on my watch-list for potential flips. If we see any of those flip on the night, it’s a Democratic wave election.”

Which seats matter the most?

Texas is a key battlefield, with former teacher and seminarian James Talarico hoping to become the first Democrat elected to a statewide office since the 1990s. Talarico, dubbed “Talafreako” by Trump, is up against the president-endorsed state Attorney-General, Ken Paxton, for a Senate seat in the historically conservative state. “If Talarico wins, it’s a banner year for Democrats,” Alpert says. “If Paxton wins, the margin will tell us a lot.”

In the swing state of Michigan, epidemiologist and Democrat progressive Abdul El-Sayed – nicknamed “Mohamed” by Trump – is up against Republican Mike Rogers for a Senate seat. Emma Shortis, a senior researcher at The Australia Institute think tank, says former president Joe Biden’s support of the Netanyahu government in Israel is “one of the key fault lines of the Democratic Party. The result in Michigan will tell us a lot about the ideological makeup and political momentum of the party ahead of the next presidential election”.

It’s lawyers at 10 paces in Alaska, a state Trump won in 2024. This time around, Democrat Mary Peltola is up against incumbent Republican senator Dan S. Sullivan and another Republican candidate, Daniel J. Sullivan Jr. Last week, the US Department of Justice filed a lawsuit requesting Alaska not to certify its Senate results if Peltola wins, arguing that having two Dan Sullivans on the ballot threatened the “integrity” of the vote count. Peltola’s team responded by asking a federal court to dismiss the Trump administration’s lawsuit, describing it as baseless and raising “profound constitutional concerns”.

Ohio is home to a hotly contested Senate race, with incumbent Republican Jon Husted neck and neck with Democrat Sherrod Brown. But it’s the battle for the Ohio governorship that has produced international headlines – in an attack ad, Republican Vivek Ramaswamy featured the estranged mother of his Democratic rival, Amy Acton, who was allegedly molested by her stepfather as a child. (The mother called her daughter a liar). The New York Times called it the “most ruthless ad of the midterms”.

Then there’s Maine, which has something of a maverick streak when it comes to politics.

The Democrats initially picked oyster farmer Graham Platner to take on veteran Republican senator Susan Collins until an allegation of sexual assault (which Platner denied) killed his candidacy. Former Maine Senate president Troy Jackson is trying to snatch the Senate seat from his five-term Republican rival Collins.

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