Da Coach can sell stuff but can he sell Rauner?

If Da Coach told us to buy snow in the middle of last year’s epic winter, many of us would have run to the store for whatever brand of the fluffy stuff he endorsed.

There’s almost nothing Mike Ditka hasn’t helped sell in the nearly 30 years since he led the only Super Bowl champion Chicago Bears.

Italian beef and pizza. Canned soup and antifreeze. Dental implants and erectile dysfunction pills. Juice boxes and beer. Cotton underwear and toilet paper. Rental cars and brand new cars. Hearing aids and frozen yogurt.

That’s a partial list of the products given Ditka’s seal of approval, generating the coach millions of dollars a year.

His magic touch has failed to extend only to Chicago’s favorite contact sport – electoral politics. And those who’ve most rigorously studied the impact of celebrity endorsements don’t expect his newest attempt at civic engagement to help Bruce Rauner’s Republican campaign for governor much, if at all.

Political endorsements from sports figures usually have even less impact on public opinion than the support of musicians, actors or media celebrities, said Beth Vonnahme, an associate professor at the University of Missouri-Kansas City.

She is one of two authors of a study titled “Mike Ditka’s a Republican? The Effect of Celebrity Endorsements on Candidate Evaluations.” The paper was presented in Chicago two years ago at a meeting of the International Society of Political Psychology. Conference topics included Syria, Libya, the euro crisis, the Tea Party — and, yes, this city’s most recognizable sports figure not named Michael Jordan.

How much celebrity endorsements matter is “highly susceptible to source credibility (the perception that the source possesses relevant expertise and is trustworthy),” according to the nationwide study by Vonnahme and Andrew Civettini of Knox College in Galesburg, Ill.

Participants in the study — who were actually asked about John Elway and Brett Favre but not Ditka, despite the paper’s title — “assessed the sports figures to be the least credible on both dimensions.”

This week, Vonnahme tried to explain it all in terms that even a Packer backer in foam cheese headgear could comprehend.

“Some people might care” that Ditka favors Rauner, she said. But that’s likely, she said, only “if he’s seen as having some credible information — if he seems to have met the candidate and knows something I don’t.”

Having watched a lot of endorsement commercials — “Some more genuine than others,” she says — Vonnahme agreed to watch a clip of the painfully awkward spot featuring Ditka and Rauner that aired during Sunday’s Bears overtime defeat.

Let’s just say Rauner and Ditka didn’t project the authentic enthusiasm of Jeff Joniak and Tom Thayer calling a close game on the radio. Ditka pounded his fist into a palm to emphasize his passion for Rauner’s fight against “the special interests.” His faux glowering wasn’t at all what we fans imagine he looked like when he was really mad, like when he busted his hand against a locker.

Further denting any notion that Ditka has special insight into local politics was the fact that Ditka votes in Florida. He isn’t eligible to even cast a ballot in the governor’s race in November.

Ditka has put little of his money where his mouth is. According to the state election board’s website, he’s made only one campaign contribution: $5,000 to the state Supreme Court campaign of ex-Bears kicker Bob Thomas 14 years ago.

In a classic interview this week with Sun-Times Springfield correspondent Dave McKinney, Da Coach himself didn’t claim any particular expertise. “This is my choice,” he said. “It doesn’t matter if I’m qualified or not. What’s qualification?”

Celebrity endorsements can have a greater impact on voters who lack “political sophistication,” the study found. Maybe Ditka can still sway some Superfans out there who pay much closer attention to Soldier Field than the statehouse.

But Vonnahme also pointed out that getting the blessing of a celebrity can backfire if the celebrity then attracts negative attention. Right after Ditka endorsed Rauner, he didn’t hesitate to comment on the controversy over video of Baltimore Raven Ray Rice battering his then-fiancée.

“His earning power is destroyed,” Ditka said on ESPN. “That’s an important thing. Here’s a young man who had a tremendous amount of earning power. It’s all gone for making a mistake.”

Take it from “Iron Mike.” He may or may not know more about political power than you. But earning power is one thing he definitely knows well.