For candidates in the Midwest, almost nothing tops a photo opportunity with a barnyard animal or a colorful anecdote about life on the farm.

Take Mary Burke, a former business executive running as a Democrat for governor in Wisconsin, who recently paused to check out the cows at a county fair. Or Illinois venture capitalist Bruce Rauner, who talks about his dairy farmer grandfather as a role model in his Republican bid for governor. And then there is Iowa U.S. Senate candidate Joni Ernst, who gained national attention with an ad touting her hog castration skills.

Most voters in these states don't work on farms. Most candidates don't either. But many of those seeking office seem to be stretching farther than ever for a barnyard background to establish common-man authenticity.