On 3 November, the United States (US) will hold midterm elections. Polls point towards a result which will change the balance of power in Washington, with the Democratic Party predicted to take control of the House of Representatives and quite possibly the Senate. Even just a Democratic victory in the House – the lower chamber of Congress – could have implications for American foreign policy.

These implications could push in two contradictory directions. On the one hand, Congress has some powers which are relevant to US foreign policy. The Senate – the upper house of Congress – must give its consent to treaties and ambassadorial appointments. Congress as a whole must approve the budget for the US military and for the country’s diplomatic agencies. It also has the power to investigate and hold to account officials who engage in corrupt or lawless behaviour. All of this suggests that a Democratic Congress could impose meaningful restraints on President Donald Trump.

On the other hand, in practice, these powers – and restraints – often amount to less than they first appear. The vast majority of foreign policy decisions do not require Congress’s approval at all. Even where approval is required, presidents have found ways to get around these constraints, acting regardless of whether Congress approves of their policy or not. And because losing control of Congress also means losing the opportunity to advance a domestic legislative agenda, the period after a midterm defeat is often when presidents turn even more of their attention to matters overseas.

US allies who are nervously watching to see which direction the country’s foreign policy heads next ought to bear both possibilities in mind. Facing a hostile Congress, Trump might become even more willing to simply ignore domestic opposition and plough ahead with controversial and unpopular policies, as he did by attacking Iran or threatening to annex Greenland. At the same time, he is likely to encounter more friction as he does so. The result could be a battle of wills between the two branches of government whose outcome is difficult to predict.

Take the war with Iran, which over the past few weeks has shown signs of entering another phase of high-intensity conflict. Democrats in Congress opposed the war from the start, and they have several tools that they could attempt to use to stop it. They could, for instance, threaten to cut off funding for the war. Or they could try to invoke the War Powers Resolution, a 1973 law which, in theory, allows Congress to compel the president to wind down an overseas conflict.

In practice, though, neither of these tools is guaranteed to be successful. Cutting off funds for an ongoing conflict in which American soldiers remain in harm’s way could be politically damaging for Democrats. And if they invoked the War Powers Resolution, Trump could simply ignore them, leaving Democrats to try to convince a sceptical Supreme Court to rein the president in.

The situation looks similar with regard to the American commitment to NATO and the defence of Europe. Republicans in Congress already passed laws – with Democratic support – which forbid Trump from drawing down US troop levels in Europe below a certain level without first consulting with allies. But these laws remain hard to enforce, even for a united Congress. Even with Democratic control of both chambers, passing new laws that place tighter restrictions on Trump’s actions would remain difficult. That is because Trump retains the ability to veto any new legislation, requiring Congress to muster up a super-majority to override the veto. That would require Republican as well as Democratic support.

Still, even stymied attempts to use the powers of Congress can still have political consequences. It might be difficult for Democrats in Congress to restrain Trump from a course of action which he is strongly committed to, but they can still raise the political costs associated with ploughing ahead. What remains unpredictable is how Trump, in the waning years of his political career, will react – by allowing himself to be restrained by political pressure or by lashing out and trying to storm through it.

Beyond the details of individual policies, something else is also at stake in these midterms for America’s allies. And that is the future of American democracy. Given Trump’s long-standing record of disputing election results he dislikes and regarding even legitimate opposition as a form of treachery, it remains to be seen how US democracy will navigate a loss for the president’s party and the two years of divided government that could follow.

In a worst-case scenario, Trump could try to interfere with the electoral process itself, plunging the country into a constitutional crisis. Even if he accepts the result, Trump may then try to use the powers of the federal government to harass and intimidate individual members of Congress – an effort which may already be underway with a federal investigation into Somali-American Congresswoman Ilhan Omar. Either of these scenarios risks deepening America’s crisis of political polarisation and undermining the shared values on which so many of America’s alliances are based.

Yet for allies yearning for the return of a more internationalist American foreign policy, the midterms could also bring a ray of hope. If the polls are right, then the political coalition that brought Trump to power in 2024 seems to be disintegrating. The Make America Great Again movement has been discredited in the eyes of many due to its association with an extreme anti-immigration agenda, a costly foreign war with Iran, and an inability to get prices under control at home. Once Trump leaves the political scene, this could point the way towards a brighter future for American allies.

But the future is not here quite yet. Trump remains the president for another two years, with all the powers that the position entails. He has one last act, and with it the ability to surprise – and dismay – America’s allies yet.

Upcoming event: Andrew Gawthorpe will be speaking at After the US Midterms: What the Results Mean for America and the World, a parliamentary discussion co-hosted by the Foreign Policy Centre and Leiden University on 10 November 2026. The event will explore what the election results mean for the next two years of US politics and foreign policy, including the implications for America’s allies and the wider international system.

Interested in attending? Please email events@fpc.org.uk with your full name, job title and organisation.

Andrew Gawthorpe is a senior fellow at the Foreign Policy Centre and an expert at U.S. politics and foreign policy at Leiden University, where he leads the ‘American foreign policy and liberalism’ research group.

Disclaimer: The views expressed in this piece are those of the individual author and do not reflect the views of The Foreign Policy Centre.