MEDINA, Minn. — As the oom-pah-pah oom-pah-pah of the band fades, Patrick Gottsch makes his way through silver-haired couples circling the dance floor at “The Mollie B Polka Party” in this quiet Midwestern town.

Mr. Gottsch, the chairman of the Rural Media Group, steps under a disco ball and issues a warning.

“As you folks in rural America know, every once in a while, you’ve got to take a two-by-four and hit the mule between the ears,” he said. “That is what we want to do now with Comcast and Time Warner.”

He says Comcast’s proposed $45 billion purchase of Time Warner Cable threatens the future of his television stations, which broadcast rural-themed shows like “The Mollie B Polka Party,” “National Tractor Pulling” and “All American Cowgirl Chicks.” And he urges the dancers, numbering about a thousand, to file protests about the merger with the Federal Communications Commission, which is reviewing the deal.

“There can’t be a wall built between urban and rural America,” Mr. Gottsch says later.

Raised on a family farm in Elkhorn, Neb., Mr. Gottsch, 61, has emerged as one of the country’s most vocal critics of the proposed media consolidation, which would reshape the video and broadband landscape. His warnings about the Comcast deal, as well as AT&T’s $48.5 billion bid for DirecTV, echo a fear that some television groups have expressed about the pending mergers: The deals would create behemoths that will use their heft to push around networks, forcing them to either cut the fees they charge for their programming or risk being thrown off the air. Some executives say the consolidation would result in challenges for new networks, especially those with niche or underserved audiences, and a lack of diversity on TV.