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By Philip Marey, Senior US Strategist, Rabobank
The first year of Donald Trump’s second term as president of the United States has led to a rapid and volatile rise in US import tariffs. Tariffs have been motivated by both economic and geopolitical reasons. The economic rationale is to bring production and jobs back to the US. However, President Trump is also using “punitive tariffs” as his weapon of choice to achieve his geopolitical ambitions. These ambitions have been dubbed the “Donroe Doctrine”, Donald Trump’s version of the Monroe Doctrine, and are spelled out in the new National Security Strategy.
However, tariffs have had negative side effects on US households, which could hurt Republican performance in the midterm elections in November. Depending on how the Trump Administration responds to weak Republican polling data ahead of the midterms, several dynamics could unfold in 2026.
Depending on how the Trump Administration responds to weak Republican polling data ahead of the midterms, several dynamics could unfold in 2026.
If the administration fears that the midterms could limit its window of opportunity to implement the Donroe Doctrine, we could see a compressed rollout of its foreign policy and trade agenda in 2026. In turn, this could make the Republicans’ midterm losses even worse, creating a positive feedback loop between the acceleration of the Trump agenda and increased midterm losses.
However, there is an off-ramp from this self-reinforcing process if the administration believes that easing or delaying foreign-policy and trade conflicts would circumvent the loss of the Republican majorities in the Senate and the House of Representatives. This would allow the administration to pursue its agenda more forcefully after the midterms.
The Donroe Doctrine
In November 2025, the White House published a new National Security Strategy. Two key sentences in this document summarise the revamped US foreign policy. The first sentence resurrected the Monroe Doctrine: “After years of neglect, the United States will reassert and enforce the Monroe Doctrine to restore American preeminence in the Western Hemisphere, and to protect our homeland and our access to key geographies throughout the region.” The second sentence added the Trump Corollary, transforming the Monroe Doctrine into the Donroe Doctrine: “We will deny non-Hemispheric competitors the ability to position forces or other threatening capabilities, or to own or control strategically vital assets, in our Hemisphere. This ‘Trump Corollary’ to the Monroe Doctrine is a common-sense and potent restoration of American power and priorities, consistent with American security interests.”
There are two aspects to the Trump Corollary: denying competitors military capabilities and control of strategically vital assets. When it comes to denying non-hemispheric competitors military capabilities in the Western Hemisphere, Venezuela and Cuba have been the main allies of the China-Russia-Iran-North Korea axis. Now that Venezuela is more or less under US control, Cuba—which has been a Russian (formerly Soviet) foothold close to the US mainland since 1959—is likely to come into focus.
The second aspect of the Trump Corollary has an economic component, as “strategically vital assets” may also include natural resources and critical infrastructure. Natural resources play a key role in Venezuela, in particular oil. An example of critical infrastructure is the Panama Canal, which President Trump targeted at the start of his second term. More recently, Trump returned his attention to Greenland. While he has stressed the importance of Greenland to US defence, there may also be economic reasons to possess the country—in particular, natural resources, such as critical minerals and oil.
Tariffs: The tool of choice and its side effects
Although we have seen that President Trump is not afraid to use military action to enforce the Donroe Doctrine, his weapon of choice is tariffs. They are used not only to protect the US economy from competitors but also for geopolitical purposes. These “punitive tariffs” are easier to implement than economic sanctions and provide a flexible instrument for foreign policy.
However, tariffs come with a cost. Initially, US importers mostly bore the higher US import tariffs imposed by the second Trump Administration, but some evidence suggests that foreign exporters and domestic consumers are covering a growing share of the bill. Moreover, higher retaliatory tariffs by foreign countries hurt US exporters’ competitive positions. Damage to international trade and higher input costs for businesses could also negatively impact investment and employment growth. The latter could further hurt US households. On top of these level effects, tariff volatility creates significant uncertainty for decision-makers in the business sector. This could further slow investment and hiring.
The tariffs’ negative economic impacts could undermine electoral support for the Trump Administration’s policies. President Trump’s approval ratings have declined for most of 2025. Although he is in his second term and therefore not up for re-election, Trump’s agenda could be derailed if the Republicans lose their majorities in the Senate and the House of Representatives in the midterm elections.
The midterm time constraint
The National Security Strategy was published in November 2025, but the Trump Administration may have only one year to achieve its objectives, with midterm elections scheduled for November 3, 2026. All seats in the House of Representatives and 35 out of 100 seats in the Senate are at stake. At the moment, the Republicans hold majorities in both chambers of Congress, but if the Democrats retake the House and/or the Senate, they could be in a position to restrict the Trump Administration’s foreign-policy actions when the 120th United States Congress is sworn in on January 3, 2027.
Whether this potential midterm time constraint is binding is still unclear. The boundaries between the legislative and executive branches will likely be tested. If the Trump Administration can circumvent checks and balances, the Donroe Doctrine could survive a midterm defeat. However, the midterm time constraint is likely to affect the administration’s decision-making throughout 2026.
Feedback loop or off-ramp?
The midterm time constraint creates the possibility of a positive feedback loop in which geopolitical tensions are compressed in 2026, with the probability of midterm losses for Republicans increasing. The negative economic impacts of tariffs on US voters could increase the likelihood of Republican midterm losses. In turn, lower polling results could spur the Trump Administration into further foreign policy and trade action.
However, there is an off-ramp for the Trump Administration amid poor polling results. In November 2025, tariff reversals were made on imported agricultural products to appease voters concerned about affordability. The key will be how the administration reacts to expected midterm losses. They might see it as a time constraint on the Donroe Doctrine. Alternatively, they may regard it as a tariff constraint: an incentive to ease tariffs, win the midterms and come back in full force in 2027 and 2028.
Conclusion
The Donroe Doctrine has shifted the focus of US foreign policy toward the Western Hemisphere, with the aim of denying non-hemispheric competitors access to military capabilities, critical infrastructure and natural resources. Although President Trump has demonstrated that he does not rule out military action, tariffs are his weapon of choice. However, both the level and the volatility of tariffs have negative side effects that could limit the window of opportunity for implementation of the Donroe Doctrine to 2026. Alternatively, the adverse effects of tariffs could incentivise the administration to ease their use until the midterms—preventing the loss of Republican majorities in the House and the Senate—and intensify them afterward. How this unfolds depends on whether the Trump Administration views the midterms as a time constraint or as a tariff constraint.
ABOUT THE AUTHOR
Philip Marey is Rabobank’s Senior US Strategist and is responsible for the bank’s US outlook. Before joining Rabobank, Philip worked as a Researcher and Project Manager at Maastricht University on various applied econometric research projects for the European Commission (EC) and the Dutch government. He also taught courses in Monetary Economics and Financial Markets at Maastricht University.