The oil industry, by contrast, remained fractured over the best prescription for what they argue are rising costs of complying with the law. Oil industry lobbyists urged Trump administration officials not to give in to an “extortion” attempt by senators, nor back down from changes they described as modest fixes needed to keep gasoline prices from spiking.

But they were outmatched. In the Midwest, the news of a possible reduction in biofuels quotas arrived as cash-strapped farmers were already growing concerned about Trump’s trade policy. Taking the teeth out of a program that helps to put a floor under corn and soybean prices would only add to their current woes, they worried. Some 38 percent of the corn crop is destined for ethanol plants, according to the U.S. Department of Agriculture.

The response was immediate. Ethanol supporters who had battled biodiesel backers on other policy matters linked arm in arm.

“With that one-two punch, there was not a segment of the industry that was not facing a severe threat to its future,” said Monte Shaw, head of the Iowa Renewable Fuels Association. “The only alternative was to try to get this on the president’s radar screen and hope that he in fact was going to stick by his promises — and he did.”