President Donald Trump made lowering prices "on Day 1" one of the signature promises of his 2024 campaign. Twenty months after his return to the White House, however, prices have moved in the opposite direction, weighed down by his tariff agenda and the war against Iran. Writing in The New Republic, columnist Virginia Heffernan argues that no word captures Trump's political predicament more sharply right now than one he rarely mentions: diesel.

"Diesel prices have surged since Trump took office, and especially since February 28, when he started the war in Iran," Heffernan writes. When Joe Biden left office at the start of 2025, diesel averaged $3.63 per gallon. This month, the price climbed past an average of $5.85 to a record high of more than $6.50. Disruptions to oil shipments, notably in the Strait of Hormuz, are pushing up crude oil prices, while reduced diesel supplies have left fuel markets tight around the world. The strait, which lies between Iran and Oman, is one of the world's key oil transit chokepoints, carrying a major share of globally traded crude. Because diesel also powers the long-haul trucks, freight rail, and farm equipment that move goods across the economy, its price is felt well beyond the pump.

Market analysts offer little reassurance. "Monday morning price average for US diesel is $6.51/gal," Tom Kloza, chief oil analyst at Gulf Oil, posted on X on Monday.

According to Heffernan, skyrocketing diesel prices "aim a missile squarely at the voters Trump can least afford to alienate" — including the truck drivers who backed him in 2024. Fully 90 percent of diesel truck buyers are men, she notes, and more than 84 percent identify as white. Citing one analysis, she adds that Republicans purchase eight heavy-duty trucks for every one bought by a Democrat. While Trump and his party have "entirely failed to calm public fears about gas prices" — Trump said "I love the inflation!" in June — she argues they have fared "far, far worse with diesel, where prices are spiking even more steeply."

The political fallout may already be visible. "About one in five Trump voters now regrets their 2024 vote, according to one opinion-research organization," Heffernan writes. Social media, she observes, is filled with once-loyal members of the "diesel demographic" raging at the president. "Hey, Donald Trump, man, it just cost me $179 to fill up my diesel!" one shirtless trucker shouts. "Six-dollar diesel is killing truck drivers!" another declares.

Heffernan highlights a September 15 video posted on X by former Rep. Marjorie Taylor Greene (R-Georgia) — once a staunch Trump ally, now one of his most scathing critics — as a prime example of MAGA frustration over diesel prices. "This is Trump's fault … It's $8.49 for diesel in California. It's $6.59 in Georgia. I don't care if it's Georgia or California. It's way too high," Greene says in the video.

In Heffernan's view, Greene is "an intuitive grandmaster of the diesel class" with "an especially keen eye for their issues: data centers, the Iran war, the Epstein files, and now diesel fuel."

"These are the issues Trump is dying on," Heffernan concludes. "By alienating the diesel class, Trump may have bitten the final hand that feeds him. Diesel is certainly the word to watch in these final weeks before the polls. If nothing else, it's excellent shorthand for the rambunctious MAGA coalition that political scientists have been trying to understand for a decade." Heffernan's "final weeks before the polls" run up to November's midterm elections, the first nationwide electoral test of Trump's second term.

Source: Alternet