The fortunes of the wonder fuel that promised to help clean the environment, secure the United States and save small family farms have steadily dwindled as environmentalists, food advocates and auto enthusiasts sour on its promise. Now that fuel, corn-based ethanol, finds itself threatened with a defection that was once unthinkable: Iowa voters.

The electorate in the early voting state often defined by its vast expanses of corn has long demanded that candidates pledge allegiance to government mandates for millions of gallons of ethanol, the homegrown product. But as the 2016 White House hopefuls traverse the state, they are seeing that Iowans have grown ambivalent.

The Republican presidential contender now polling strongest in Iowa, Sen. Ted Cruz, is campaigning on an energy platform that would have been a death wish in elections past. Cruz is an unabashed opponent of giving ethanol any special government help. He derides it as the worst kind of central planning.

“Voters here are just not that interested in ethanol anymore,” said Steffen Schmidt, a professor of political science at Iowa State University. “You don’t even hear the word come out the mouths of candidates much.”

There are myriad reasons, not the least of which is a modern-day Republican electorate that takes pride in bucking the established order and is increasingly absolute in its disdain for subsidies. But it is also about the shifting politics of renewable fuels in a state where small family farms have given way to much bigger agribusinesses. Only a fraction of the state’s voters work in the corn industry these days.

It is all compounded by troubles befalling the decade-old ethanol mandate, signed into law by George W. Bush, that transcend Iowa. Cars are more efficient and people are driving fewer miles than the drafters of the law had anticipated, leaving auto manufacturers to warn that engines are at risk of malfunction if the government doesn’t ease quotas of ethanol blended into retail gasoline.

Environmentalists once hopeful the product would help curb global warming now caution that it may be just as harmful as fossil fuels.