The cable channel Newsmax on Wednesday accused Fox News of illegally cornering the market for conservative TV news, an unusual escalation in a long-running rivalry between two cable television networks.

In a case filed in U.S. District Court in Miami, Newsmax laid out what it called “an exclusionary scheme” by which it said that Fox News used bare-knuckle tactics to block its competitors and establish a near-monopoly in right-leaning pay TV news.

“Fox has pursued a coordinated, behind-the-scenes campaign to suppress Newsmax” from reaching more viewers, the lawsuit said.

Newsmax argued that Fox News and its parent company, Fox Corporation, had in effect created a financial penalty for cable and satellite distributors that want to carry Newsmax on their basic, entry-level tier of channels.

According to the suit, Fox often demands that a distributor choosing to include Newsmax on that basic tier carry additional Fox-owned networks, such as Fox Business, and pay extra fees to do so, the lawsuit said.

“I think it’s bad for a democracy to have only one major media network on the center-right on television,” Christopher Ruddy, the owner of Newsmax, said in an interview on Wednesday.