During a recent campaign stop in Iowa Republican presidential candidate Ben Carson said the promise of the Renewable Fuel Standard (RFS) needs to be kept through 2022.

“(A)s far as the Renewable Fuel Standard is concerned, there were certain promises that were made that extend out until 2022. And many people, you know, invested a lot of time, energy and resources based on those promises that were made. Those promises have to be kept,” said Carson during an appearance at Northwestern University in Orange City, Iowa on December 18.

According to America’s Renewable Future (ARF), Carson made similar comments at stops in Council Bluffs and Carroll, Iowa this month.

“Carson’s grasp of the issue of the RFS has tightened and we are glad to see him recognize the importance of keeping the promise made to investors and the 73,000 Iowans whose livelihoods depend on it,” said America’s Renewable Future State Director Eric Branstad.

ARF will be releasing a final report card in early January designating each candidate as either good or bad on the RFS. ARF will let Iowans know where the candidates stand through paid media and grassroots efforts.

Listen to Carson’s comments here: GOP candidate Ben Carson on RFS