John Stossel‘s latest column at Human Events explores the politics of government ethanol mandates.

Cars run on fuel. Politicians run on votes, and they’ll do almost anything to get them. That includes supporting mandates that force us to use ethanol, a fuel made from corn that Iowa farmers grow.

They support ethanol because Iowa is the first state to vote on presidential candidates. Candidates want to look strong at the start of the race, so every four years they become enthusiastic ethanol supporters. Even those who claim they believe in markets pander to Iowa’s special interests.

Donald Trump, who doesn’t seem to have a consistent political philosophy aside from bashing critics and foreigners, now has joined the ethanol-praising club. In fact, Trump says regulators should force gas stations to increase the amount of ethanol they use. It’s a convenient way to attack his Iowa rival, Sen. Ted Cruz, R-Tex., who courageously says the mandate should be phased out.

Cruz is right. Legally mandating that a certain percentage of fuel used be ethanol is a bad idea for several reasons:

First, mandating ethanol means more land must be plowed to grow corn for fuel. The Department of Energy estimates that if corn ethanol replaced gasoline completely, we’d need to turn all cropland to corn — plus 20 percent more land on top of that.

Second, requiring ethanol fuel raises the price of corn — bad news for consumers who must pay more for food.

Third, although ethanol’s supporters claim burning corn is “better for the environment,” that’s not true. Once you add the emissions from growing, shipping and processing the corn, ethanol creates more pollution than oil.