Investing.com -- Shares of major U.S. refining companies and diesel futures declined Wednesday following a report that the Trump administration is preparing to ban diesel exports for 90 days in an effort to reduce domestic energy prices ahead of the midterm elections.

Marathon Petroleum fell 1.5%, while Valero Energy dropped 1.9% and PBF Energy declined 2.9%.

U.S. ultra low-sulfur diesel futures were also trading more than 6.3% lower. Europen diesel futures surged as much sa 7% higher.

According to the report, the administration is working on the ban despite internal disagreements and opposition from the oil industry. The legal process for implementing the restriction is still being developed.

The proposed ban would mark the first restriction on U.S. energy exports since the Obama administration ended a decades-old oil export ban in 2015.

A 90-day export ban could initially lower diesel prices in some U.S. regions as fuel shipments originally bound for Europe or Asia would be redirected into the domestic market, increasing supply. The oil industry has warned that refiners would likely reduce production in response to losing a major export market, which could lead to higher prices later.

Diesel prices in the U.S. are at historically high levels.