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Blue Tsunami, Same Waters? US Foreign Policy after the Midterms

The ‘blue tsunami’ in the US midterms opens a new phase for American politics. The Democratic Party has won a majority in both chambers of Congress. Taking the House was expected, but conquering a majority in the Senate seemed out of reach until a year ago, let alone by such a margin (55-44 seats, with Alaska still to assign). Domestic concerns drove the result, chiefly affordability and perceived corruption in government. Yet both are linked to voters’ rejection of the administration’s most disruptive foreign policy move: the war against Iran. The conflict pushed up fuel prices and deepened the sense that government is detached from people’s daily lives. President Donald Trump himself conceded that the war, launched last February alongside Israel, was at least partly to blame for the Republican defeat. Vice President JD Vance was more forthright still, restating after the vote his long-standing opposition to the conflict.

The effects of this ‘blue tsunami’ on US foreign policy will depend on the interaction of three factors: the institutional balance within the US constitutional framework; the tools of political pressure available to the Democratic majority in Congress; and long-term trends in US foreign policy.

The powers of the lame duck

The first factor is an institutional framework that is unbalanced toward the President on international affairs. Foreign policy remains an area where the President retains broad discretion. Trump can threaten to veto any bill that Congress passes to reverse his administration’s international record. That goes from the Iran war and military support to Israel, to the threat of disengagement from European security, rapprochement with Russia and protectionist trade policies. The President can also keep governing by executive order, a tool he has used more than any predecessor, including on tariffs and sanctions. None of this is new. After a midterm defeat – a recurrent event in the American system even if rarely on this scale – “lame-duck” presidents often turn to foreign policy to build their legacy, as their room for manoeuvre at home shrinks.

How Congress can fight back

Still, a Congress opposed to the President has tools to hinder him abroad too. This is the second factor, and it starts with the Congress’ authority over spending. The National Defense Authorization Act (NDAA) – the federal law setting spending caps for the Department of Defense (and much more) – is a prominent example. In 2025, the Republican-majority Congress already used it to contain the Trump administration’s plans to disengage from European defence, which had alarmed European capitals. Democrats are likely to use it to protect US commitments further. They will also refrain from sowing intra-European divisions by supporting anti-EU parties on the continent, contrary to what the administration has been doing so far.

The limits of a Democratic reset

Here, however, the third factor comes into play. Pressing European allies to invest more in their own defence is a structural feature of US security policy, not merely a Trump demand. More fundamentally, Washington’s strategic priorities have been shifting away from Europe for years, towards the Indo-Pacific. As noted by IAI’s Alessandro Marrone, the 2025 US National Security Strategy lists the Western Hemisphere as the first priority of US foreign policy, followed by the Indo-Pacific and Europe – in this order. The midterms are unlikely to reverse this hierarchy. A renewed engagement with Europe could also be constrained by the progressives’ scepticism towards the role of the US as the “world policeman”, as Michigan Senator-elect Abdul El-Sayed recently stated, and by a growing fiscal deficit.

On Ukraine, a Democratic Congress will be able to oversee the Prioritized Ukraine Requirements List (PURL), the NATO initiative through which allies buy US weapons systems and transfer them to Ukraine. Democrats have also floated the possibility of introducing a brand new 15-billion-dollar package to resume direct support to Kyiv. However, any Democratic shift would meet objective limits, such as the gaps in US stockpiles left by the war in the Middle East. Enhanced pressure on Russia would also be contested by the White House. Trump has recently proved that he is willing to challenge Congress when it comes to relations with Moscow, by suspending the implementation of sweeping sanctions introduced by a bill named after the late Republican Senator Lindsay Graham and approved by a Republican-led Congress. He will be even more combative vis-à-vis an adverse Congress.

On trade as well, Congress could reassert its constitutional prerogative over tariffs and stop presidents from imposing them unilaterally. But at the same time, a more confrontational stance towards China could develop within the powerful Congressional committees dedicated to relations with Beijing, especially by further curbing US advanced technology exports. A Democratic return to a more open model of world trade is thus far from certain. The Biden administration itself spearheaded more protectionist industrial policies with far-reaching implications for US relations with commercial partners, the Inflation Reduction Act among them.

A shifting relationship with Israel

Democratic pressure will be most intense on Iran, where the party can raise the political cost of continuing the war. The Democratic Party’s relationship with Israel is undergoing a profound transformation. According to a Pew Research Center poll published in April 2026, 80 per cent of Democrats and Democratic-leaning independents now have an unfavourable view of Israel, up from 53 per cent in 2022. The elections have confirmed that the shift extends well beyond the party’s progressive wing, favouring the emergence of a unifying position: moderate Democrats such as re-elected Georgia Senator Jon Ossoff and Texas Senator-elect James Talarico have taken increasingly critical positions towards Israel, particularly over its conduct in Gaza and US military assistance. In Congress, Democrats could now derail the section of the NDAA that mandates deep integration of the Israeli and US military-industrial complexes.

Even the Republican side is not completely immune to a potential reconfiguration of relations with Israel and on the war. On election day itself, Trump floated the idea of ending military aid to Israel, arguing that the country no longer needs it. If Vance and the Republican Party’s isolationist wing win the internal fight in the coming months, Washington may be more inclined to cut its losses in Iran through a negotiated exit, even if Trump loathes the idea of appearing a “loser”.

In general, the Democrats will be able to increase political pressure on the administration through Congress’s investigative powers, by withholding funds to continue the conflict, and by delaying the Senate’s confirmation of executive appointments. It cannot even be ruled out that a War Powers Resolution might be passed to reassert Congress’s authority over the launch of military conflicts and thereby limit Trump’s room for manoeuvre. But Trump retains discretion, for example, over maintaining the naval embargo against Iran.

A more ambivalent ally

The elections therefore raise more questions than they answer. After two turbulent years of Trump’s presidency, US allies may be tempted to breathe a sigh of relief. But they should think twice. Trump will remain in office for two more years, albeit with a divided government and a weakening grip on a political system that will soon turn to the 2028 presidential race. He could be tempted to lash out against allies while its hands are increasingly tied at home. Democrats may adjust the Congress’ stance on international affairs, but structural limits will constrain them too. Any major shift must also reckon with the fact that, while voters rejected the status quo, they have not wholeheartedly embraced a traditional liberal foreign policy. The US as an ambivalent ally and increasingly isolationist power is likely here to stay.


Luca Barana is Senior Fellow for Europe at the Istituto Affari Internazionali (IAI).