The Environmental Protection Agency on Thursday will officially deny oil refiners' request to change the Renewable Fuel Standard so they don't have to blend ethanol and other biofuels to comply with the national fuel mandate.

The EPA submitted the formal notice of denial to the Government Publishing Office on Wednesday, which is slated to publish the decision in Thursday's edition of the Federal Register.

The notice of denial would appear to be the final chapter in a long, protracted attempt by Trump confidante and adviser Carl Icahn, representing independent refiners, to change the "point of obligation" under the RFS, which would require fuel retailers to meet the EPA blending requirements rather than oil refiners.

"In evaluating this matter, EPA’s primary consideration was whether or not a change in the point of obligation would improve the effectiveness of the program to achieve Congress’s goals," a pre-publication copy of the notice read. "EPA does not believe the petitioners or commenters on the matter have demonstrated that this would be the case."

The change would have freed the refiners from having to buy expensive renewable identification number (RIN) credits because most independent refiners do not have the ability to blend ethanol and other biofuels in the country's gasoline and diesel supplies to meet the RFS goals.

"EPA believes that a change in the point of obligation would unnecessarily increase the complexity of the program and undermine the success of the RFS program, especially in the short term, as a result of increasing instability and uncertainty in programmatic obligations," the notice said.

The notice of denial falls the same day the EPA is expected to finalize the ethanol and renewable fuel blending requirements for 2018 as it is required to do under the law.

EPA Administrator Scott Pruitt is reportedly expected to visit Iowa in the coming days, which critics say is indicative of Pruitt's support for the ethanol industry over the refiners.

Iowa is the country's top ethanol producer. The state's Republican senators were successful in getting Trump to reiterate his support for the RFS by directing Pruitt to rescind an earlier proposal to begin cutting the RFS blending requirements over the next two years. Pruitt has sent letters to the senators expressing his support for ethanol and the RFS and pledging to support the program.