Earlier this month General Mills came out in opposition to Minnesota’s marriage amendment ballot measure. Now supporters of the proposed amendment have launched a boycott of General Mills, imploring consumers to dump their Cheerios, Yoplait, and the myriad other products the Golden Valley manufacturer makes and markets.

The National Organization for Marriage said Tuesday, June 26, that it is initiating a protest of General Mills and has launched a website with an online petition in response to General Mills taking a public position on the amendment, which seeks to preserve Minnesota law that defines marriage as the union of a man and a woman.

The website, dumpgeneralmills.com, said it had gathered more than 8,000 signatures by Tuesday evening.

“We’d like (General Mills) to step back and say they respect the views of all of their customers and employees,” said Jonathan Baker, director of the Corporate Fairness Project for the National Organization for Marriage. “Eating Cheerios for breakfast shouldn’t have to be a moral choice about marriage.”

The Washington, D.C.-based organization is urging corporations in Minnesota to remain neutral on the issue. The group launched a similar boycott of Starbucks in March after the Seattle-based coffee company came out supporting legislation legalizing same-sex marriage in Washington state. A ballot measure there, if passed, would reverse that legislation.

The Minnesota amendment, if passed by voters in November, would enshrine Minnesota marriage law into the state constitution. Failure of the amendment would not change existing state law.

Baker said 45,000 consumers have joined the group’s “Dump Starbucks” campaign. Supporters of the legislation in Washington state counter that they’ve collected more than 650,000 supporters for a “Thank You, Starbucks” drive. Baker acknowledges he’s uncertain what bottom-line impact the campaign has had on Starbucks.

“I don’t suspect it has damaged Starbucks’ bottom line just yet, but I can tell you that there are 45,000 consumers that have committed to no longer do any purchasing there,” he said. “At some level, that shows up on their books.”

It doesn’t appear to be showing up yet. In its most recent quarter, revenue for Starbucks Corp. grew 15 percent to $3.2 billion.

For consumers, it’s easier to boycott a heavily branded company like Starbucks that sells mainly just brewed coffee in its own stores and coffee beans and ground coffee in grocery stores. General Mills, on the other hand, has a broad and diverse portfolio of brands and markets them under such varied names such as Totino’s, Cascadian Farm and Green Giant.

“It’s much easier to boycott Starbucks than boycott a General Mills or P&G or any number of corporations that have multiple independent, powerful brands,” said Akshay Rao, a professor of marketing at the Carlson School of Management. To effectively honor the boycott, consumers would have to bring a long list of products that are off limits on their shopping trips. By Rao’s count, General Mills has 42 different brands boycotters would have to avoid.

Supporters of the Minnesota marriage amendment are protesting this week across the street from General Mills’ corporate headquarters, urging people to bring the company’s products for donation to food shelves.

In a statement, Tom Forsythe, company vice president of corporate communications, said: “We acknowledge the strongly held views on all sides of this question. We respect and defend the right of others to disagree. But General Mills has worked to create an inclusive culture for our employees for decades. As a Minnesota-based company, we believe it is important for Minnesota to be viewed as inclusive and welcoming as well.”

Ken Charles, General Mills’ vice president of global diversity, announced the company’s stand on the question in a blog post June 14.

Julie Forster can be reached at 651-228-5189. Follow her at twitter.com/bizbeatPiPress.