With the US midterms less than a month away, what's at stake?

There are just over three weeks to go until the U.S. midterm elections, which will determine control of the legislative branch of the U.S. government.

On Nov. 3, the U.S. will go to the ballot box to elect all 435 members, about one-third of the Senate (35 out of 100 seats), as well as decide on a host of state and local contests, such as governors' races in 36 states, like California.

So how is the makeup of the U.S. government expected to change, are there any unexpected outcomes, and how might it affect the world?

Democratic resurgence

Just after Republican Donald Trump had won back the White House over Democratic nominee Kamala Harris.

When Republican Donald Trump won back the White House over Democratic nominee Kamala Harris in 2024, pessimism about the Democrats’ future was at a fever pitch.

So for polling to show two years later that the party is heavy favourites to take back the House of Representatives, the lower house, and has a realistic chance of winning the Senate, implies a remarkable turnaround in their fortunes.

The Silver Bulletin, the outlet set up by polling analyst Nate Silver that tracks U.S. polls, shows the Democrats leading Republicans on a generic ballot.

The generic ballot is a general question about which party respondents prefer, without dealing with the specifics of individual candidates (for example, you may not like a political party, but you may like your local MP from that party, affecting how you vote).

The Economist’s model suggests, at the time of writing, that the Democrats have a 94 per cent chance of winning the majority, and a likely outcome is that they would win enough seats to give them a significant majority.

Trade tariffs, energy prices, and cost of living

Donald Trump won the 2024 presidential election by targeting cost-of-living issues, and claimed that his opponent, Kamala Harris, would lead the U.S. to a new war.

Since taking office in 2025, he has introduced punishing trade tariffs on practically every country on the face of the earth, started a trade war with China, and an actual war with Iran.

While Trump claimed that it would be the tariffed countries that would ultimately pay more to sell to the U.S., in actuality, the price of the tariffs has been passed on to the U.S. consumer.

The Iran war's impact has been wide-ranging, even going so far as to potentially damage U.S. global prestige, but its most salient impact has been the restriction of energy supplies passing through the Strait of Hormuz.

That restriction of the Strait has led to surging energy prices globally, and in the U.S. the price of diesel has risen by about two-thirds since the start of the war.

Diesel is used in significant quantities by both the logistics and the farming industries, meaning that if Trump's recent actions to lower the price of diesel do not succeed, it will exacerbate the cost of living even more than it already has.

This is not to mention that even if he were to be successful, it might already be too late to impact the midterm elections.

These two factors have contributed significantly to rising inflation, resulting in the U.S. Federal Reserve raising interest rates.

And the Senate too

The House changing hands is not that surprising; it is not uncommon for the midterms to be punishing incumbents.

The House went to the opposition against Trump in 2018, but also against Joe Biden in 2022, Barack Obama in 2010, George W. Bush in 2006, to give a few examples from this millennium alone.

Losing the Senate is not exactly rare either, but this year was expected to be particularly difficult for Democrats, as strong Republican states are holding elections for senators, such as Texas, Kansas, Alaska, and Ohio, to name but a few.

The Atlantic described a Democratic victory in the Senate as “far-fetched” as late as a year ago, but now predicts the party has a 60 per cent chance of pulling it off.

Another factor is that Trump’s falling popularity in states considered “safe”, such as Texas, is having a knock-on effect on Senate races.

Trump recently held a third rally in Texas in a single month. He was supporting Texas Republican Ken Paxton, against Democrat James Talarico.

While Reuters reports the rally was “packed”, it took resources away from other races, just to ensure victory in a state that he won by a huge margin just two years ago.

What does it mean if the Republicans lose the House and Senate?

If Trump loses the midterms, there are concerns, or hopes depending on where you stand, that he will effectively be a “lame-duck” president.

This means that he will no longer be able to effect significant policy, especially domestically, as a hostile legislature forces him to either retreat from or significantly water down controversial policies.

While the House and Senate cannot unilaterally withdraw troops from conflicts like Iran, they can place limits on funding, limiting what actions can be taken.

There is an expectation that the Democrats will try to impeach Trump again, as well as investigate him and his allies for rule breaches, although it should be noted that even a successful impeachment requires a supermajority in the Senate to remove Trump.

But perhaps most prominently, should a Supreme Court justice step down or pass away after the midterms, it will be the Democrats who decide whether Trump’s nominee will be accepted, or if it will come to a vote at all, as a Republican-controlled Senate did in the final year of an Obama administration.

This is less of a hypothetical issue than usual, with Samuel Alito hinting that he was considering retiring soon.

Overall, a change in midterms is expected to significantly change how Trump behaves.

While his opponents hope that it will limit his actions, some believe that the lame-duck scenario will lead him to behave more aggressively and erratically.

But the prospect of a total loss, once thought nigh impossible, now verges on reality.