A group of 15 Texas Republican House members, led by Rep. August Pfluger, is threatening to derail the more than $1 trillion farm bill over a Senate provision expanding ethanol blending requirements. The lawmakers argue the measure, backed by Midwestern senators and corn-state interests, would raise costs for Texas oil refineries and push fuel prices higher. The dispute revives a long-running fight between the agriculture and oil industries over federal ethanol mandates dating to 2005. The House already passed its version of the farm bill in April; the Senate has yet to act before the current congressional session ends in January, and Texas farm groups worry the ethanol dispute could further delay final passage.