US diesel prices have surpassed the average during Joe Biden's presidency, reaching $4.09 a gallon under Donald Trump's second term, compared to $4.08 during Biden's tenure. This surge, exacerbated by the conflict in Iran and subsequent supply disruptions, adds pressure on the Trump administration ahead of the midterm elections.

Diesel, crucial for industries like agriculture and transport, has seen its price climb 43% to $5.37 a gallon following US and Israeli bombing campaigns against Iran, which led to the closure of the Strait of Hormuz. While global crude oil prices have fallen, diesel remains elevated due to low inventories, limited refining capacity, and Russia's export ban. Analysts like Tom Kloza note that diesel, unlike gasoline, is likely to remain tight.

High energy prices are a significant concern for voters, with an AP-NORC poll showing Trump's approval at 33% and four in 10 voters citing fuel costs as a major stressor. Oil majors like Exxon Mobil and Chevron have reported significant profits amid these price hikes, drawing criticism from the president.