The outcome of the midterm election will shape policy in the United States for years and have repercussions around the globe. Decisions made in Washington affect both US adversaries such as Iran and countries such as Ukraine, which is seeking more US support.

President Donald Trump does not have the final say when it comes to deciding where the United States goes to war or which countries get financial or military aid. While the president wields more power in the US than in parliamentary democracies such as Germany, he does not govern alone — even in the land of opportunity.

The House of Representatives and the Senate, the two chambers of Congress in which the Democratic Party secured a clear majority on Tuesday, wield considerable influence. They decide on legislation and government spending and also serve as a check on the president and the intelligence agencies.

The president can veto legislation passed by Congress. Congress can override that veto with a two-thirds majority in both chambers. The legislature also handles impeachment proceedings. In addition, the president can only appoint Cabinet members, US ambassadors and federal judges from a list of nominees the Senate approves.

In the 2024 US election, the Republican Party secured not just the White House through Trump's reelection but also both chambers of Congress, which made it easier for the US president to govern.

The Democrats' resounding midterm victory has now flipped control of both chambers, which could shift the direction of major foreign policy issues.

Ukraine may see little benefit from Democrat wins

Joe Biden, a Democrat, was in the White House when Russia launched its invasion of Ukraine. Alongside Europe, the US stood out as a reliable partner, supporting Ukraine with financial aid, military expertise and, above all, large-scale weapons deliveries.

The situation changed abruptly under Trump. Ukrainian President Volodymyr Zelenskyy  famously received a notably frosty welcome during his 2025 visit to the White House. Trump now openly admits that he gets along better with Russian President Vladimir Putin than with Zelenskyy.

The US has suspended sanctions against Russia and reduced financial and military aid to Ukraine. Now the Democrats have majorities in both chambers of Congress, they could put increased support for Ukraine on the agenda.

"Democrats criticize the Trump administration for not doing enough for Ukraine," Brandon Conradis, a former DW journalist and now an editor at Bloomberg Government, told DW before Tuesday's election. "They can push legislation that would provide more aid to Ukraine."

If Trump vetoed such legislation, the outcome would depend on the balance of power in Congress. But a two-thirds majority could override his veto with support from some Republicans. 

Is Trump trying to end the war in Ukraine, or helping Putin win it? 

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Can Democrats end the Iran war?

Trump launched the war against Iran alongside Israel on February 28, 2026, without consulting Congress. Under the US Constitution, Congress must approve a formal declaration of war against another country. Democrats have repeatedly voted against the war and even passed a resolution, together with some Republicans, calling for an end to the hostilities. The Trump administration has ignored it.

"I don't think Congress will have huge powers here," said Michael O'Hanlon, director of research for foreign policy at the US think tank Brookings Institution, told DW before the midterm elections, but added that Congress could perhaps prevent a major escalation by refusing to fund it.

How the midterms could impact US development aid

US support for aid projects around the world that help fight Ebola, AIDS and hunger was sharply cut back by President Trump shortly after he began his second term. Among other measures, he shut down USAID, the US agency responsible for foreign development assistance.

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Whether a Democratic-controlled Congress could "reactivate" the agency against the president's wishes is questionable. But Congress could push for increased aid spending and investigate the controversial closure of USAID.

"Democrats would have oversight power and use it to scrutinize the closing of USAID," Conradis said. "There will be hearings, and they will drag officials they view as responsible in front of Congress."

Ultimately, the US remains a country with a Republican president. There will be no complete reversal, of course. "It's not like if Democrats win control of Congress, everything is going to change. But some things will change because the power dynamics will be different."

This article was originally published in German on November 3, 2026. It was updated on November 4, 2026, to reflect the outcome of the midterm election.