A White House official on Wednesday denied a news report that said the US is preparing a 90-day ban of diesel exports in an attempt to control record prices for fuel widely used by farms, trains and trucks.

Diesel prices have shot to records over $6.50 a gallon as the wars in Iran and Ukraine constrain deliveries of oil and fuel products, a political risk for President Donald Trump ahead of the midterm elections.

US Energy Secretary Chris Wright said earlier that such a ban would not work and could boost gasoline and jet fuel prices, and that the US was discussing voluntary measures.

After the Politico report said the US was preparing a 90-day ban on the exports, Wright said nobody is considering a flat ban on shipments of the fuel.

“What’s being discussed is what’s the most efficient way to get more diesel into the United States of America, and continue maximum flows of gasoline and jet fuel,” Wright said without offering more details.

(Reporting by Timothy Gardner; Editing by Chris Reese and Nick Zieminski)