Trump says he backs banning US diesel exports to bring prices down, but the move would likely push gasoline prices up instead — bad for drivers, farmers, and Republicans heading into the midterms.

• Diesel costs have jumped, and farmers say they can't afford fuel for the fall harvest.
• A ban wouldn't help the Midwest — its refineries already run flat out and don't export anyway.
• Gulf Coast refiners would simply refine less oil, which means less gasoline and higher gas prices.
• Even Trump's own energy and interior officials say the ban would not lower prices.
• Republicans in Iowa and elsewhere are pushing the idea mostly as a talking point while polls show them losing badly, including in Texas.

Outlook: A ban looks unlikely given the warnings inside the administration, though a Jones Act shipping waiver could still slip through as a consolation move.