The long-expected announcement is something of a reward to Iowa Sen. Chuck Grassley, who as Senate Judiciary Committee chairman led a contentious but successful fight to confirm Brett Kavanaugh to the Supreme Court. The veteran Republican lawmaker is the Senate’s leading ethanol proponent and sharply criticized the Trump administration’s proposed rollback in ethanol volumes earlier this year.

At that time Grassley threatened to call for the resignation of the Environmental Protection Agency’s chief, Scott Pruitt, if Pruitt did not work to fulfill the federal ethanol mandate. Pruitt later stepped down amid a host of ethics investigations.

A senior administration official said Monday that the EPA will publish a rule in coming days to allow high-ethanol blends as part of a package of proposed changes to the ethanol mandate. The official spoke on condition of anonymity ahead of Trump’s announcement.

The change would allow year-round sales of gasoline blends with up to 15 percent ethanol. Gasoline typically contains 10 percent ethanol.

The EPA currently bans the high-ethanol blend, called E15, during the summer because of concerns that it contributes to smog on hot days, a claim ethanol industry advocates say is unfounded.

In May, Republican senators, including Grassley, announced a tentative agreement with the White House to allow year-round E15 sales, but the EPA did not propose a formal rule change.

Lifting the summer ban is expected to be coupled with new restrictions on trading biofuel credits that underpin the federal Renewable Fuel Standard, commonly known as the ethanol mandate. The law sets out how much corn-based ethanol and other renewable fuels refiners must blend into gasoline each year.