UPDATE: The news conference has ended.

UPDATE: Gov. Reynolds holds news conference. Watch live.

ORIGINAL: Senator Chuck Grassley says he may seek to block President Trump’s nominees for key posts at the Environmental Protection Agency unless the administration backs off a proposed reduction in the volume of biofuels blended into gasoline.

Sen. Grassley said in a phone call with reporters Tuesday he plans to speak with EPA Administrator Scott Pruitt about the Renewable Fuel Standard. Pruitt has proposed targets for 2017 and 2018 set slightly below current levels following a push by oil companies to ease mandates for using ethanol from corn and soybeans.

Grassley said EPA’s proposed rollback would result in job losses in Iowa. Pruitt's position is in contrast to the staunch support for the biofuel industry Trump pledged as a presidential candidate last year.

Iowa Governor Kim Reynolds is also upset over the EPA’s Renewable Fuel Standards. She has called a news conference tomorrow to address what she says is a ‘growing threat to renewable fuels.’

That news conference will be in Pella at 1:30 pm Wednesday.

U.S. Senator Tammy Duckworth (D-IL) wrote an op-ed in

today, outlining her opposition to President Trump’s nominee to oversee the implementation of the Renewable Fuel Standard.

Senator Joni Ernst says she has met with the EPA Administrator about the Renewable Fuel Standard saying, “Iowa is the largest producer of ethanol and biodiesel in the nation. Our farmers, ranchers and rural communities depend on maintaining a strong RFS. Time and again, the RFS has proven to be a major driver of alternative fuels and economic development.

“Throughout his confirmation process, Administrator Pruitt promised me multiple times that he would uphold the spirit of the RFS, as intended by Congress."