US diesel prices have hit a record $6.06 a gallon as Donald Trump’s war in Iran and Ukrainian attacks on Russian refineries choke fuel supplies globally, triggering new fears of inflation. The surge reflects a deepening energy supply shock that is reverberating through the economy just weeks ahead of midterm elections that will decide who controls the US Congress. Average prices for US diesel — the lifeblood of American industry and agriculture — now substantially exceed the average set under Trump’s predecessor Joe Biden.

Diesel’s critical role in the transport supply chain is also feeding into surging producer prices, which can stoke inflationary pressures at a time when Americans increasingly feel squeezed by affordability. Global diesel markets are under severe pressure due to the conflicts in Ukraine and the Middle East, which have restricted flows to customers in Asia and Europe. This has elevated the US’s prominence as a petroleum products exporter and drained domestic stockpiles.

The jump in diesel comes ahead of the autumn high season, where the fuel is used to power agricultural equipment to harvest and transport crops. Grain farmers in America’s Corn Belt have said they are facing a crisis with rising fuel and fertiliser prices eating into profits. Inflation is an issue for US voters, with prices rising by 3.4 per cent in July.

Consumer prices are 28 per cent higher than before the Covid-19 pandemic. Trump has justified the high prices as a necessary evil in taming the nuclear threat posed by Iran. But voters are increasingly frustrated with Trump’s handling of the economy and the cost of living.

A recent FT poll showed that his approval rating has fallen to its lowest level, with just 33 per cent of registered voters approving of his performance as president.