Can Democrats stop Iran war, reverse Trump’s tariffs after midterms win?

Democrats have taken control of the United States House of Representatives and Senate in Tuesday’s midterm elections in a scathing defeat for US President Donald Trump’s Republican Party.

The Congress that will convene in early January will be radically different from the first two years of Trump’s second presidential term, which saw Republicans holding majorities in both chambers.

While Democrats will have greater power to scrutinise Trump’s policies and obstruct any legislation they oppose, there is still a lot a president can do without congressional approval.

Here is a look at some pressing political issues and how a Democratic majority in both chambers might affect them:

Trump has acknowledged the role the war on Iran has played in Republican losses in the midterm elections. “I think a part of it was Iran, but at the same time, people understood the importance of what I’ve done with Iran,” Trump said during a telephone interview with Fox News.

Frustration among voters about inflation, and the rising cost of fuel and groceries have been among the main factors behind their rebuke to Republicans. Democrats tapped into this by campaigning heavily on affordability and domestic spending.

Trump embarked on the war on Iran with Israel in February without congressional authorisation. He could still order attacks, but he could also face constraints from the new Congress. Lawmakers could use their power to deny additional funding when the current government-funding bill expires on December 11, presenting a critical budget constraint on Trump’s military decisions.

However, James Boys, research fellow at the Centre on US Politics at University College London, said that while Congress may wish to cut off funding, it may not be straightforward. “With troops in theatre, this would prove to be highly problematic and be seen to be placing American lives at risk,” he said.

Analysts also said the War Powers Resolution is unlikely to succeed in reining Trump in. Previous attempts to use the 1973 federal law have been defeated or rendered ineffective.

The War Powers Resolution states that a president can repel an imminent attack, but military actions must end within 60 days unless Congress declares war. The president can then issue a veto, which can only be overcome by a two-thirds supermajority in both the House and Senate.

The projected breakdown of the newly elected Congress shows that Democrats are well short of those supermajority thresholds.

Scott Lucas, professor of international politics at the UCD Clinton Institute in Dublin, Ireland, said that while Congress is constrained without a two-thirds majority, what it could do is propose legislation by “working with some Republicans who might distance themselves from Trump” after the resounding declaration of dissatisfaction voters have given the president in these midterm elections.

For example, he said, “JD Vance, the vice president, opposed the war and has done so from the start.” Last week, Vance sent a letter to Iran’s security chief in a reported effort to revive talks and avert further attacks.

“[Will] he now push even harder to end the war?” Lucas asked.

However, Boys said the fact that Trump no longer faces election himself because the US Constitution requires him to leave office at the end of his second term may make the president instead feel that “he is now unleashed to act with impunity on the world stage”.

“Indeed, given his weakened domestic political circumstances, one can easily imagine Donald Trump escalating policies in the Middle East as he seeks to establish an indisputable presidential legacy,” he added.

Last year, Trump unleashed tariffs of 10 percent to 50 percent on about 90 countries with the aim of shrinking the US trade deficit. The move, which rattled global markets, was struck down by the Supreme Court in February, but the Trump administration has found workarounds to that ruling.

Days after the Supreme Court’s 6-3 vote, Trump doubled down on the tariffs, quickly signing an executive order based on a different statute and raising them from 10 percent to 15 percent. However, those tariffs are limited to 150 days unless they are extended by Congress.

Democrats have blamed Trump’s tariffs for exacerbating the rising cost-of-living crisis as tariffs ultimately fall back on US importers who pass them on to consumers. They accused Trump of “pickpocketing the American people”. A Democratic-controlled Congress could push for exceptions that would give exporters some temporary relief, but any deeper shift in US trade policy will have to wait for the 2028 presidential election and the new occupant of the White House.

Boys said the “situation regarding tariffs remains before the United States courts” and whether the government must give back tariff money it has already collected – and exactly how much of it – remains in dispute.

The one area in which Congress is expected to follow through regardless of the flip in party control is in passing tougher restrictions on China’s access to technology. These include the Remote Access Security Act, which would extend export controls to remote access of US goods, software or technology, and the Chip Security Act, which would require companies to verify that advanced artificial intelligence chips remain in authorised locations to prevent diversion to foreign adversaries.

Lucas said one major outcome of the midterm vote is that Democrats will now assume the chairmanships of all congressional committees, which have the power to launch investigations and subpoena witnesses.

This could result in scrutiny of the Trump family’s vast business empire, the president’s ties with the late sex offender Jeffrey Epstein and Defense Secretary Pete Hegseth’s handling of the war with Iran. They could even try to impeach Trump for a third time over the conflict.

Congress also may – and plans to – launch extensive investigations into the Trump administration’s immigration policies. Democrats have repeatedly advocated for using their new subpoena power to scrutinise collaboration between the US tax agency, the Internal Revenue Service, and the Department of Homeland Security on the Trump administration’s policy of deporting refugees and migrants.

Detaining people at airports and hearings in their immigration cases became part of Trump’s efforts to carry out mass deportations – one of his 2024 campaign promises. In the lead-up to Tuesday’s elections, Fox News released a poll that found 53 percent of registered voters felt the immigration crackdown had “gone too far”.

The Homeland Security Department has argued that about 70 percent of its immigration detainees are criminals, if pending charges are factored in. But critics have questioned that statistic, given that the legal system in the US gives suspects the presumption of innocence until they are proven guilty in a court of law.

Lucas said the midterm vote means “Democrats and responsible Republicans can now reach out to the state and local communities and encourage them to pursue recovery and responsible policies.”