What Trump losing power over Congress means for Iran, Ukraine and foreign policy

US President Donald Trump speaks at a midterm campaign rally at the Rock Hill Sports & Event Center in Rock Hill, South Carolina on Oct. 29, 2026.

Kent Nishimura | AFP | Getty Images

With Democrats taking control of Congress, U.S. President Donald Trump could intensify his focus on foreign policy in his final two years in office, while facing greater scrutiny over the wars in Iran and Ukraine, experts told CNBC.

The Associated Press is projecting Democrats will have a Senate majority, flipping seats from Republicans in Iowa, Kansas, North Carolina, Ohio, South Carolina, and Texas.

Democrats also won control of the House, giving the party greater scope to scrutinize the administration, shape spending and challenge Trump's foreign-policy agenda.

"We are going to see a president that is somewhat constrained on matters of oversight and investigation, but on foreign policy, he does still retain a lot of latitude," Laurel Rapp, director of Chatham House's U.S. and North America Programme, told CNBC's "Squawk Box Europe."

Rapp said the Iran war was a "major issue" in this election cycle amid soaring fuel prices, food costs, and inflation. The war began when Trump launched joint strikes with Israel on Feb. 28.

Iran war powers

"Republicans don't really have an off-ramp here at this stage. We know the Democrats will seek to take votes in the House and the Senate to constrain the Republicans, to restrain the administration on Iran war powers. But whether that will bind the administration is another matter," Rapp added.

She said that Democrats could exercise the "power of the purse" to limit spending on U.S. military and other Iran-related costs.

With control of both chambers, Democrats could pass legislation seeking to direct Trump to end U.S. involvement in the conflict. However, making such a measure binding over a presidential veto would require enough votes in Congress to override it.

J.C. Lintzenich, visiting senior fellow at the German Marshall Fund, said that the president is not a "lame duck."

Trump retains authority

"Remember that this election changes the Congress; it does not change the president," Lintzenich told CNBC's "Squawk Box Europe" on Wednesday.

"The President of the United States still has lots of power, lots of authority. We still have pending action in Iran. We still have an unresolved situation with Russia and Ukraine."

He added that while Congress has changed, foreign policy is still executed by the president and his appointed officials.

"What we'll now see is a little bit more congressional oversight, the application of funding, for example, Ukraine, that's required by statute and law," Lintzenich said.

Lintzenich said the outgoing Congress was "more willing to let the White House slide," but Democratic control of both chambers would mean a more assertive Congress, using its Article I powers over legislation, spending, and oversight to hold the White House more closely to existing law and congressional requirements.