FOREIGN policy is rarely the deciding factor in United States midterm elections, when economic considerations usually drive voters' choices.

But this time, with Donald Trump's war against Iran and his sweeping tariff campaign pushing up costs for Americans, a president's approach to world affairs has itself become a pocketbook issue.

As the Nov 3 elections approach, there are growing signs that voters are drawing that connection directly, creating a major liability for Trump and his fellow Republicans and imperilling their control of Congress.

Those include a Reuters/Ipsos poll earlier this month showing some 78 per cent of Americans blame Trump's policies for rising prices that are outpacing their earnings.