The ethanol lobby is getting scared.

The ethanol mandate has no clearer enemy among top-tier presidential candidates than Ted Cruz. And in Iowa, where ethanol has for decades held a mystical sway over politicians of all stripes, the clear front-runner in next month's caucuses is Ted Cruz.

If Cruz wins Iowa, especially if he wins big, it will confirm that the subsidies and mandates for ethanol are very important only to a sliver of the population (largely the lobbyists and executives of the giant agribusinesses that receive the lion's share of the benefit).

If Iowa voters don't really care about the ethanol mandate, then the ethanol lobby is a paper tiger. If the ethanol lobby is a paper tiger, then the federal ethanol mandate is not long for this world.

Ethanol is a fuel made from grain — most importantly corn. For decades, federal and state governments have subsidized ethanol. Currently, the most important subsidy is the Renewable Fuel Standard, which requires refiners to pour some ethanol into their gasoline. Ethanol is less efficient than gasoline, and environmental groups curse its effects on greenhouse gases, water levels and soil quality. The mandate obviously clashes with the free-market principles Republicans profess as well.

Iowa, at 2.37 billion bushels in 2014, produces more corn than any other state. Most Iowans, including Republican voters, support the RFS. In a December poll, 61 percent of Iowa Republicans said they support the mandate, while 34 percent oppose it. At first glance, that confirms that the mandate is popular. But take a second look: a full one third of Iowa Republicans oppose corporate welfare for Iowa.

Dig deeper and ethanol looks less like a third rail in Iowa. A May 2015 Selzer & Co. poll found Iowans split evenly (45 percent to 46 percent) on whether "Subsidies are a waste of government money — including past subsidies for ethanol and wind energy."

This anti-subsidy mindset is a fruit of the Tea Party, which was born in the wake of the Wall Street bailouts. Being a conservative today increasingly means opposing big-government handouts to special interests, even to "your own" people.

In the 2012 cycle, Selzer & Co. also asked Iowa Republicans how big a deal ethanol subsidies were, and only 14 percent said subsidy opposition was a "deal killer," while 40 percent said it was "no real problem." "Iowa Republicans' long reputation for being hostile to political candidates who oppose ethanol subsidies isn't true today," wrote Des Moines Register political reporter Jen Jacobs at the time, "if it ever was."

"It never comes up," Rand Paul told me in Waukee, Iowa, last month. He could recall only two instances of anyone in Iowa asking him about the issue, and both times they were paid activists, either for or against the mandate. Ted Cruz's campaign staff told me something similar.

"Voters here are just not that interested in ethanol anymore," Iowa political scientist Steffen Schmidt told the Associated Press in December. "You don't even hear the word come out the mouths of candidates much."

Chris Christie has the endorsement of Iowa's preeminent Republican businessman Bruce Rastetter — who has made millions off of ethanol subsidies. Christie chides the Obama administration for not implementing the mandate more aggressively. Donald Trump attacks Cruz for opposing it. Marco Rubio and Jeb Bush have tried to fudge on the issue.

Cruz has clearly and repeatedly said he would wind down the mandate in about three years — faster than any of his opponents. And now he could win Iowa.

So the industry has gone into panic mode. Eric Branstad, a spin instructor and the son of the Republican governor, is being paid by the ethanol lobby group America's Renewable Future to stalk Cruz around Iowa. The group leaves glossy fliers on the chairs of Cruz events, warning that "Ted Cruz is Dangerous" because of his mandate opposition.

Here's the thing: the ethanol lobby has been attacking Cruz for months — including harsh radio spots — and it hasn't stopped Cruz from moving into first place.

Now, the ethanol industry has to attack harder, because they know what a Cruz caucus victory would prove: that there is no significant public support for their industry's biggest subsidy.

A Cruz win, especially amidst the ethanol lobby's full-court press, would show that all the other politicians who pandered to the corn cronies were fooled. Hillary Clinton and Chris Christie, and dozens before them, all saw the subsidy enthusiasm of the special-interest lobbyists who came bearing checks, and these candidates assumed there was a grass-roots army behind them.

Maybe the pandering politicians and the ethanol lobbyists are right. Maybe you can't win Iowa while opposing goodies for ethanol. But if Cruz punctures that myth, subsidy lobbyists of all stripes will have reason to worry.

Timothy P. Carney, The Washington Examiner's senior political columnist, can be contacted at tcarney@washingtonexaminer.com. His column appears Tuesday and Thursday nights on washingtonexaminer.com.