Sen. Ted Cruz of Texas on Wednesday urged President Trump to overhaul the federal ethanol mandate during a rally with refinery workers at Philadelphia Energy Solutions, which has cited the cost of complying with the biofuel standard as the major cause of its recent bankruptcy filing.

The former Republican presidential contender was invited by the refinery's management and labor union to attend a town hall event at the South Philadelphia complex before hundreds of workers, including those from other area refineries. The refiners say the federal Renewable Fuels Standard imposes high costs on merchant refiners. Cruz has made the ethanol mandate a major issue in his Senate reelection campaign this year.

PES has become a flash point in an escalating war between the oil and corn ethanol industries over the renewable fuel mandates. The ethanol industry says the Philadelphia refinery's own business decisions led to its bankruptcy.