U.S. President Donald Trump on Thursday will gather rivals from the oil and corn industries for the second time this week as the administration seeks elusive common ground on reforms to the nation’s controversial biofuels law. The meetings come amid rising concern in the White House over the current state of the U.S. Renewable Fuel Standard (RFS), a law requiring refiners to mix biofuels such as corn-based ethanol into their fuel, which has increasingly divided two of Trump’s most important constituencies. A refining company, Philadelphia Energy Solutions (PES) in the key electoral state of Pennsylvania, last month blamed the regulation for its bankruptcy.A meeting earlier in the week ended with Iowa Republican Senators Chuck Grassley and Joni Ernst calling the White House efforts to help refiners cope with the regulation a threat to farmers, and vowing to fight proposed changes.Grassley and Ernst, along with Republican Senators Ted Cruz and Pat Toomey of refining states Texas and Pennsylvania, will be in attendance again on Thursday, according to two sources familiar with the planning of the event.A number of companies will also be represented.