DES MOINES — Before Saturday, Wisconsin Gov. Scott Walker had publicly supported ending a mandate on ethanol in fuel.

But at an Iowa agriculture summit Saturday, emceed by a major state Republican donor, suddenly the mandate and the Renewable Fuel Standard that sets it didn't seem like such a bad idea.

"It's something I'm willing to go forward on, continuing the Renewable Fuel Standard," Walker said to applause from a crowd of hundreds of farmers and others in the agriculture industry, although he later introduced the possibility scaling it back over time.

The apparent shift was illustrative of the tension presidential candidates, Republicans in particular, encounter when they parachute in to Iowa.

On the one hand, many Republicans support cutting government spending and ending longstanding subsidies, the renewable fuel standard among them. But corn, from which ethanol is produced, is major crop in Iowa and a driver of the state's economy — and Iowa farmers aren't keen to see incentives to purchase ethanol rescinded any time soon.

Every presidential cycle, candidates must decide whether to pander to Iowa and farmers in hopes of winning over the Hawkeye State — or not.

Sen. Ted Cruz opted firmly for the latter option Saturday, aiming instead to make a point about his own ideological steadfastness.

"I don't think Washington should be picking winners and losers," Cruz said frankly.

It "would be the easy thing to do," Cruz said, to simply say, "I'm for the RFS, darn it."

But he isn't, and Cruz instead delivered a stern rejection of campaign-trail pandering.

"People are pretty fed up, I think, with politicians who run around and tell one group one thing and tell one group another thing," Cruz said.

"There are a lot of politicians who are going to tell you whatever you want to hear," Cruz said later. "I'm willing to bet I'm not the only person here who's been disappointed with politicians in Washington, who's tired of people blowing smoke."

"I'm going to do what I said I'm going to do, Cruz added, "and I'm going to tell you the truth."

Cruz received some applause for his principled stand — but not as much as was awarded to those candidates who stood up for ethanol.

"It's not just 'It's Iowa, it's a caucus state, we better suck up to them," said former Arkansas Gov. Mike Huckabee. "We need the broadest possible energy portfolio so America will never at a point be held hostage."

Among those candidates who did not wholly support the renewable fuel standard, however, most approached the subject with fuzzier rhetoric than Cruz.

Former Florida Gov. Jeb Bush said he could envision a rollback "at some point." New Jersey Gov. Chris Christie used the same language, but tried to relate to the farming crowd nevertheless.

"New Jersey is the Garden State, remember," Christie said.

Former Texas Gov. Rick Perry, a former Texas agriculture commissioner, said he does not support such a measure at the federal level at all.

But Perry drew the crowd in with personal stories of having grown "up on a cotton farm, 16 miles from the closest place that had a post office in a house that didn't have running water," and of watching "my wheat go to hell in a handbasket."