"Despite the rhetoric of the merging parties, the inevitable result is that consumer end up with fewer choices and higher prices," he said.

Silver was joined by representatives of the Consumer Federation of America and the Communications Workers of America, a union that represents thousands of workers employed by each company. Also on board was Gilles BianRosa, CEO of video startup Vuze, which petitioned the FCC last year to take action against Comcast for throttling Internet traffic on its network.

The participants spoke of the merger as a done deal, though a formal announcement isn't rumored to come until next week, at the earliest. With a rumored $30 billion price tag, the deal would indeed be a blockbuster.

The complex transaction appears to be on hold as NBC Universal appeals to French company Vivendi to shed its 20 percent stake in the entertainment company. The deal would see Comcast take a controlling 51 percent share, leaving NBC with the remaining 49 percent of the joint venture.

Free Press has dedicated a special section of its Web site to the opposition campaign, which will lean on lawmakers and antitrust authorities and anyone else who will listen to its message that the deal would involve major a major consolidation of the media landscape, while bringing together content distribution in a union that would give Comcast every incentive to promote NBC's programming at the expense of other networks.

Under the screaming block letters reading "No Merger!" Free Press writes:

"Talk about a bad marriage. Comcast, the nation's largest cable company, is getting hitched to NBC, one of the world's biggest producers of TV shows and motion pictures. For consumers, it means higher prices, fewer choices and less innovation. This is one wedding we need to stop!"

Silver noted that the Obama administration has made it clear that it intends to "reinvigorate the nation's antitrust laws," which could include a lengthy review of the merger, and approval only with significant conditions, such as the divestiture of NBC's broadcast affiliates and firm commitments to keep its online content available on non-Comcast Web sites, such as Hulu, the joint venture between NBC and News Corp.

"Hulu is the perfect example of nascent competition on the Internet platform as a threat of the market power of the cable distributors," said Mark Cooper, research director with the Consumer Federation of America. "Given the magnitude of the merger, we think the simpler and more direct way to preserve competition would be to just say no."