Over the past four years, the men who ran the Republican and Democratic governors’ associations competed fiercely. Now, they’re going into business together.

RGA executive director Phil Cox and his DGA counterpart, Colm O’Comartun, are forming 50 State LLC, a bipartisan consulting firm that will help corporate clients navigate state governments.

The pairing may be less unlikely than it seems. The gubernatorial associations have had a less acrimonious relationship than the parties’ Senate and House campaign arms. That’s partly because the RGA and DGA can collect unlimited corporate money, and some nonideological donors give money to both.

So Cox and O’Comartun found themselves making regular joint appearances in boardrooms before shared patrons.

In an interview with POLITICO last week to unveil their new venture, the duo recalled executives taking notice of their rapport as they briefed them on the map of competitive races.

“They’re so used to seeing people shout at each other on Chris Matthews or Bill O’Reilly that they couldn’t believe we can get along,” said O’Comartun, 46.

“We could disagree without being disagreeable,” added Cox, 40.

They plan to maintain from 10 to 15 corporate clients, some of which will have likely contributed to the governors associations.

The president invites all 50 governors to the White House for dinner each winter during the National Governors Association meeting. It became a tradition for O’Comartun and Cox to go out to dinner, along with their wives, the night of that gathering.

The couples met before this February’s dinner and got to talking about their long-term plans. They discussed how the top Washington firms typically have strong federal practices, but their efforts in the states can sometimes be an afterthought.

“With D.C. mired in gridlock, the real action and opportunity is at the state level,” said Cox.

50 State will not lobby or consult for political clients, but both principals plan to stay personally active in campaigns. They will provide clients with strategic and public relations advice. The firm will also give corporations the ability to run state-level issue advocacy campaigns when necessary, such as to pass or defeat ballot initiatives.

O’Comartun is outgoing Maryland Gov. Martin O’Malley’s right-hand political man and will play a key role if the Democrat runs for president.

“He has so many talents and an ability to understand relationships,” O’Malley said in a phone interview.

Cox would likely help a Chris Christie presidential bid, possibly managing the campaign or directing the pro-Christie super PAC, though the New Jersey governor is still devising his plans for a likely run.

Cox and O’Comartun insist that any roles on 2016 campaigns would not affect their plans for the firm. They intend to launch immediately with half a dozen staffers and then scale up.

There is precedent for operatives of opposing parties going into the consulting business together. Former Bill Clinton White House Counsel Jack Quinn and Republican operative Ed Gillespie teamed up to create Quinn Gillespie in 2000, which became a successful lobbying firm. Gillespie, who became Republican National Committee chairman, later sold his stake.

Gillespie chaired Bob McDonnell’s winning 2009 campaign for governor of Virginia, which Cox managed. Cox helped advise Gillespie’s first run for office this year, in which he nearly upset Democratic Sen. Mark Warner.

“Phil Cox is one of the best strategic thinkers I know,” Gillespie wrote in an email.

The new partners argue that the kind of issues businesses deal with on the state level generally aren’t hyper-partisan and often align with the interests of governors and legislators: good schools, better health care outcomes and often cheaper energy.

O’Comartun has policy bona fides and spent a career in academia before entering politics; Cox is more of a pure political animal, with two decades of experience managing campaigns.

Cox, a Massachusetts native who attended the University of Virginia and lives in McLean, ran local and state races before overseeing McDonnell’s 2009 victory. During the 2010 cycle, he directed political operations in eight states, including Pennsylvania and Florida, where Republicans gained key governorships. He became executive director the next year.

O’Comartun, who lives in Baltimore, was born and educated in Ireland. He worked at Tufts University’s Fletcher School of Law and Diplomacy, directed Alumni Programs at the Kennedy School of Government at Harvard University and led the Irish Institute of Boston College.

During O’Malley’s first term as governor, O’Comartun oversaw several agencies. The governor describes him as his “aide-de-camp.”

After being reelected in 2010, O’Comartun told O’Malley that he wanted to become executive director of the DGA, which O’Malley had been tapped to chair.

The governor credits O’Comartun with improving fundraising, making field programs more sophisticated and strengthening opposition research.

In one irony, Christie and Cox decided to put the RGA into debt to spend $1.2 million in Maryland just before last month’s midterms. The late blitz helped defeat Anthony Brown, O’Malley’s lieutenant governor and handpicked successor.

As O’Malley put it, “progress zigs and zags.”

Larry Hogan, the Republican governor-elect of Maryland, was certainly grateful for Cox’s help.

“You’d be hard-pressed to find anyone with a better understanding of state policy and politics than Phil,” he said.