They’re coming for big cable, and the wind is at their backs. The growing alliance of companies and nonprofit groups opposing the proposed merger between Comcast Corporation and Time Warner Cable Inc. nearly doubled in size Monday, adding 12 new members in the fight to convince federal regulators to block the deal on antitrust grounds.

The growth spurt for Stop Mega Comcast -- as the group is called -- came on the same day that the Federal Communications Commission restarted the informal countdown clock to review the merger, after pausing the review process for the second time three weeks ago. The new additions bring the coalition’s total membership to 27 public interest groups, labor unions and for-profit companies.

And they’re just getting warmed up.

Jeffrey Blum, senior vice president and deputy general counsel for Dish Network Corporation, a coalition member, said Tuesday he expects Stop Mega Comcast to grow even larger as the review process continues. “We welcome anyone who opposes the merger,” Blum told International Business Times.

Blum said the coalition is planning a round of intense lobbying efforts to “educate” lawmakers in Washington, D.C., about what he said are serious competitive harms posed by the proposed merger that would combine the country’s two largest cable companies into a Goliath. Although Blum declined to speculate how much money the coalition’s members are spending to oppose the merger, he said it likely “pales in comparison” to Comcast’s lobbying budget.

Lobbying data from the Center for Responsive Politics show Comcast outspent almost every other company on Capitol Hill last year, racking up almost $12 million and employing more than 40 lobbying firms. Stop Mega Comcast, in turn, enlisted the Washington, D.C.-based lobbying firm Glover Park Group, the same company hired by Discovery Communications to fight the merger. In addition to Dish Network, the group also counts Glenn Beck’s TheBlazeTV among its for-profit members.

Comcast has written off Stop Mega Comcast as a group of “self-interested opponents.” The coalition’s newest members comprise mostly advocacy groups, including the Consumers Union, the Rural Broadband Alliance and the National Asian American Coalition. The lone for-profit company among the new additions is the fledgling cable network Z Living (formerly Veria Living), whose chief executive, Eric Sherman, has been vocal about his difficulty in securing a carriage deal with Comcast.

Comcast’s proposed $45 billion takeover of Time Warner Cable would give it control of more than a third of the country’s pay TV and broadband markets. Opponents say the combined company would gain an unfair bargaining advantage, allowing it to stifle competition from emerging content companies such as Netflix Inc. and Inc.  

Launched in early December, Stop Mega Comcast was spearheaded by the nonprofit group Public Knowledge, whose co-founder, antitrust lawyer Gene Kimmelman, is a former chief counsel at the U.S. Department of Justice who, ironically, helped approve Comcast’s merger with NBCUniversal in 2011. Kimmelman has been a staunch supporter of blocking the Comcast-Time Warner Cable deal.

In a statement Monday, Kimmelman said the diverse array of groups and companies that have signed on to Stop Mega Comcast speaks volumes about the deal’s far-reaching implications.

“Even in the face of Comcast’s well-known penchant for retaliating against companies that dare oppose it, organizations of all types are joining together to say this merger is not in the public interest,” he said. “We encourage all interested organizations and stakeholders to join our fight against this merger.”

Christopher Zara is a senior writer who covers media and culture. Got a news tip? Email me here. Follow me on Twitter @christopherzara.