If it passes, it would reduce corn demand, probably by enough to have a significant impact on corn prices in both Canada and the United States.
But because of that likely impact, politicians with farmer constituents are likely to oppose it.
The two senators leading the push for eliminating the mandate both have oil refineries in their bailiwicks.
They are Republican Senator Pat Toomey from Pennsylvania and Democratic Senator Bob Menendez from New Jersey.
They say that other biofuels have lower greenhouse gas emissions, though ethanol proponents argue the product is a good option to help fight climate change now.
Before the ethanol mandate became law, the U.S. government often paid heavily to compensate corn producers facing low prices.