U.S. diesel prices hit an all-time high on Thursday, while gasoline remained stubbornly elevated near $4.10 a gallon, intensifying political pressure on the Trump administration as it struggles to convince voters it can tame inflation ahead of the November midterm elections.

The national average for diesel reached $5.820 a gallon Thursday, according to GasBuddy data cited by Reuters, narrowly eclipsing the previous record of $5.819 set on June 17, 2022, in the wake of Russia’s invasion of Ukraine. Gasoline, meanwhile, has climbed sharply in recent months and now averages around $4.10 a gallon—still below the all-time national record of $5.016 from June 2022, but high enough to pinch household budgets at a politically sensitive moment.

Crude oil benchmarks also extended their rally Thursday, with Brent rising to $95.78 a barrel and West Texas Intermediate climbing to $91.64, marking four consecutive days of gains and their highest levels in about six weeks.

The spike in diesel prices carries particular economic weight because the fuel is the backbone of the trucking, agricultural, construction, and shipping industries. Higher diesel costs therefore ripple far beyond the pump, increasing transportation and operating expenses for businesses and ultimately pushing up the prices consumers pay for food and other goods.

The latest surge is rooted in the ongoing U.S. military conflict with Iran, which continues to disrupt energy markets and slow shipping through the Strait of Hormuz. Those supply disruptions have hit diesel especially hard, given its heavy use in commercial logistics.

The price increases create a difficult backdrop for President Donald Trump’s efforts to make affordability a central theme of his midterm campaign, as Republicans defend their congressional majorities. Trump has taken steps aimed at easing consumer costs, including recent meetings with oil executives to explore ways to increase fuel supplies and bring down gasoline prices. He has also promoted an agreement involving Venezuelan oil as part of a longer-term strategy to boost supply.

But the president has acknowledged that relief may not come quickly. In remarks reported by The Hill, Trump said prices would eventually come down but could not say whether that would happen before the election—a notable admission given that fuel prices are one of the most visible measures of the cost of living, with changes at the pump immediately felt by drivers and businesses.

The affordability issue is expected to play a major role in the November elections, with Trump pledging to campaign aggressively for Republican candidates in roughly 35 key races, according to Reuters. The renewed energy-price surge adds another complication for the administration’s economic message. While the White House has emphasized efforts to increase energy supplies and lower consumer costs, the latest diesel record underscores the difficulty of insulating the U.S. economy from disruptions in global oil and refined-fuel markets.

For consumers, the immediate concern is straightforward: diesel has never been more expensive, and gasoline remains well above pre-surge levels. With the midterms approaching, the cost of keeping Americans on the road is likely to remain an increasingly prominent part of the broader affordability debate.