FORTUNE — In an election season that’s given voters many firsts, we can add public sniping and fact-checking by blue-chip companies to the list.
Last week’s dustup between the Romney camp and Detroit automakers started with what seemed like a pretty typical dig in campaign ad-inundated Ohio. Romney’s ad: “Barack Obama says he saved the auto industry. But for who? Ohio or China?”
Claims that car companies are shipping American jobs overseas have been largely debunked by outside groups. What wasn’t typical was the debunking directly from GM GM and Chrysler, putting a new twist on an already-acrimonious election cycle now in its final hours.
“Politics at its cynical worst,” was the choice phrase GM spokesman Greg Martin used to describe the ad to The Detroit News. Sergio Marchionne, CEO of Chrysler’s parent company Fiat, wrote in a memo to employees, “Jeep assembly lines will remain in operation in the United States and will constitute the backbone of the brand.” He concluded: “It is inaccurate to suggest anything different.”
That kind of backlash from a publicly traded company is almost unheard of in contemporary politics. “I’m a historian and I get paid to think about this kind of thing, and I can’t think of another analog,” says Harvard Business School professor Nancy Koehn, who studies corporate leadership. “This isn’t like some celebrity CEO saying, ‘Hey, I’m going on a roadshow because I want to save animals.’”
These sorts of direct political statements are still rare in the genteel world of Fortune 100 companies. Most firms still work in a political system characterized by backroom dealing and soft-money corporate political donations routed through front groups. But as the lines between business and politics continue to blur, Americans can expect to see more public pronouncements. Indeed, it could very well be a “canary in the mine shaft” moment, Koehn says.
Normally, businesses exercise their campaign muscle through donations. “Companies will give politically,” says Bill Freed, president of the Center for Political Accountability. “But it’s much less likely that they will speak out.” Chevron CVX , for example, gave $2.5 million to John Boehner’s super PAC earlier this month, but declined to elaborate on its reasoning in a comment to the Washington Post.
As some companies speak up, though, many are growing increasingly aware that political talk is a minefield, Freed says. Last year, some 85% of major companies had adopted higher standards for its political spending disclosure, according to research from the Center for Political Accountability. Anything to keep from turning into the next Target tgt , where a $150,000 contribution to a group running ads for an anti-gay candidate triggered boycotts.
In some ways, Romney’s Detroit ad forced a response. “There’s nothing more important to them than the fact that they are American companies and American brands,” says Richard Levick, president of communications firm Levick. “The car companies had to do this because it was at the core of the very brand where they were being attacked. They viewed these as anti-car commercials.”
But Levick also believes that GM and Chrysler’s lashing out is not simply the product of an ugly campaign season and brewing PR crisis. Such a move by two iconic American companies will pave the way for others to follow suit, he argues, as Washington raises the stakes. “I think it [will] happen again,” he says. “The first casualty of war in politics is truth.” He adds: “And the rumor is that the 2016 campaign season begins on Thursday.”
This election has been huge for corporate interests, despite the unusual nature of the GM rebuttal. Unprecedented amounts of company dollars have been funneled into a vast campaign finance network. However, much of the money has come from smaller companies and wealthy individuals. Larger corporations have been hesitant to step into the fray, outside of the occasional CEO outburst. Of course, there are notable exceptions: an increasing number of CEOs have called for a reasoned solution to the deficit.
Typically, the phrase “corporate interests” evokes images of a shadow network of CEO overlords that control the country’s destiny. And sometimes the fears seem justified. But if more companies follow GM and Chrysler’s lead, it could bring some transparency to corporate political involvement. “Lobbying is all about investing through the backdoor,” says Koehn. “This is like calling a spade a spade on a public stage, and in that way it’s kind of refreshing.”
No matter who wins Tuesday, we can expect more business in politics, offstage and on.