Trump’s global agenda flies into domestic headwinds

It would appear that US President Donald Trump continues to dominate US foreign policy. In the latest example, Trump unilaterally decided to join Israel in launching a war against Iran, and Congress failed to pass the Iran War Powers Resolution to curb his authority to do so.

Yet not everything is as it seems. Mounting domestic constraints on his executive authority are narrowing his room for manoeuvre — a dynamic likely to sharpen as the November midterm elections approach. With his political window potentially closing, Trump may accelerate efforts to cement his imprint on the international system. Last week, for example, he quipped that Cuba might be next.

But domestic trends should concern Trump. Recent polling shows that 45% of Americans now prefer a less active US role in world affairs, up from 33% last year. While foreign policy may not top voters’ priority lists, that indifference should not be mistaken for acquiescence when Trump pushes controversial initiatives.

Public opposition has been clear in several recent cases. Roughly 73% of Americans opposed Trump’s proposal in January to seize Greenland from NATO ally Denmark. Prior to the war against Iran, only about 30% of Americans said they trusted his handling of the situation, including potential military strikes. After the start of the war, Trump could not muster more than 50% support for the war, according to the latest Fox News poll. And while the raid that removed Venezuelan President Nicolás Maduro drew 39% approval, 40% opposed it, with 55% expressing little confidence in how the administration handled the aftermath. Public scepticism toward Trump’s foreign policy is tangible — and could intensify if Americans perceive mounting costs or risks. In just a few short days, the US has already lost at least 13 service members in the war against Iran.

Institutional constraints are also tightening. On 20 February, the Supreme Court delivered a major blow by curbing Trump’s use of reciprocal tariffs under the International Emergency Economic Powers Act (IEEPA). Tariffs have been central to Trump’s foreign policy toolkit, which is used to pressure allies and adversaries alike. While the administration has imposed new universal 15% tariffs outside the IEEPA framework and may pursue sector-specific measures, the ruling makes clear that sweeping and indefinite tariff authorities are not limitless. Resetting rates below earlier reciprocal levels may ease tensions with partners, but the decision underscores that executive flexibility has boundaries.

Congress, too, is reasserting itself. Its attempt to pass the Iran War Powers Resolution predictably failed, because the Senate and House voted along almost exclusively partisan lines. But the fact that it happened in the first place should alarm the Trump administration.

More broadly, lawmakers from both parties have demanded greater transparency regarding military strikes on Iran, forcing the Trump administration to provide multiple briefings to them since the war began. This week, Democratic Senator Richard Blumenthal, a member of the critical “Gang of Eight” responsible for overseeing the White House’s national security and foreign policy, indicated that he was extremely concerned about the Trump administration’s Iran war, especially the risk to American service members and the high costs of the conflict. Following the Venezuela operation, members of the Gang of Eight expressed frustration at not being adequately briefed.

The House — despite a narrow Republican majority — voted in bipartisan fashion to revoke US tariffs on Canada. As midterm campaigning accelerates, Democrats are poised to frame Trump’s foreign policy, particularly tariff-driven cost increases, as harmful to working-class Americans. Even some Republicans are signalling discomfort with aspects of the administration’s approach. They include senators such as Rand Paul, Susan Collins, Lisa Murkowski, and Thom Thillis.

Compounding these pressures are domestic political distractions. The bipartisan vote compelling the Department of Justice to release the files of convicted sex offender Jeffrey Epstein has injected uncertainty into the political environment. Trump’s reported appearances in the documents and questions surrounding their handling have fuelled renewed scrutiny. Regardless of the legal outcome, the episode contributes to a climate of instability that complicates the administration’s broader agenda, including foreign policy messaging and diplomatic engagement.

Cracks are also emerging within the MAGA coalition itself. Trump campaigned on ending “forever wars” and prioritising narrowly defined American interests. Yet critics within his own movement argue that deeper engagement in the Middle East and continued global activism contradict that pledge. Representative Warren Davidson, a Republican from Ohio, broke with his party and voted in favour of the Iran War Powers Resolution. He argued that “America First was supposed to be a rejection of the globalist war machine.” Republican Representative Thomas Massie from Kentucky also staunchly opposes the war.

Other prominent voices, such as former Republican congresswoman Marjorie Taylor Greene and conservative commentator Tucker Carlson, have publicly questioned aspects of Trump’s foreign policy, particularly regarding Israel and Iran. There are already rumours of a deep and growing fissure within the Trump administration on foreign policy because of the Venezuela and Iran operations. If the war with Iran widens, Trump could face backlash from the very constituency that elevated him.

Taken together, public scepticism, judicial limits, congressional oversight, and intra-party divisions are generating meaningful friction on Trump’s global agenda. None of the factors on their own will be decisive. But collectively, they threaten to constrain the administration’s strategic bandwidth and raise the political costs of bold foreign policy gambits.

For Southeast Asia — and the broader international community — this evolving dynamic is likely to result in a president who may feel incentivised to act decisively abroad to project strength and secure a legacy before political capital erodes further. He could, for example, seek to implement new tariffs that extract additional concessions from Southeast Asian countries and that limit or bar them from future cooperation with America’s great power rival, China.

The paradox of Trump’s second-term foreign policy is thus becoming clearer: while he retains substantial authority, the guardrails are strengthening. As the midterms approach, the struggle between executive ambition and domestic restraint is likely to lead to more confusion and policy uncertainty, as well as an erosion of US credibility, leadership authority and legitimacy. This dynamic will shape not only America’s political trajectory, but also the stability of the international order.

This article was first published in Fulcrum, ISEAS – Yusof Ishak Institute’s blogsite.

Related: Why America fights alongside Israel as China holds back in Iran | The costs of quick power: America’s Iran strike | What does the Iran crisis mean for the global economy?