William “Mo” Cowan, who served a brief term as an interim US senator earlier this year, has accepted a position with a prominent Boston law firm as chief operating officer of its government relations affiliate.
After completing a fellowship at Harvard’s Institute of Politics in November, Cowan will become chief operating officer at ML Strategies and rejoin the Mintz Levin law firm, where he worked before signing on as Governor Deval Patrick’s chief legal counsel in 2009.
Cowan, 44, told the Globe he plans to split time between Boston and Washington, D.C., helping clients “navigate some of the tricky challenging waters, particularly those that interact with government.”
He said he had entertained a number of private-sector offers, but “this seemed like the most exciting and enticing opportunity.”
“They’ve been very generous, and it’s a competitive salary,” Cowan said, declining to go into more detail. “More than anything, it’s a chance to build on my experiences and work with some old friends.”
Patrick appointed Cowan, who had been his chief of staff for nearly two years, to the interim Senate post after John F. Kerry resigned to become Secretary of State. After Edward J. Markey was elected in June, Cowan resigned in July, saying he wanted to explore the private sector and ruling out a bid for elected office.
Asked Tuesday if, after a three-month break from politics, he had entertained notions of running, Cowan’s voice rose in incredulity and he laughed, “For office? No, no, no.”
At ML Strategies, Cowan joins a firm led by president Stephen Tocco and William F. Weld, former governor. He is barred by a federal statute from lobbying Congress for two years from his July departure from the Senate and by a state law from Beacon Hill lobbying until February.
But Cowan left open the option of registering to lobby in the future.
“It’ll depend on the role as it is at the time, but I’m joining MLS to offer my strategic insight and perspective to the clients,” he said. “If that involves me lobbying at some point in the future, then we’ll explore it.”
Officials at Mintz and ML Strategies said they planned to lean on Cowan’s experience locally and nationally.
“He’s got perspectives on things that very few people get to have,” said Mintz managing partner Robert Bodian. “He’s that much more well-rounded and interesting.”
Tocco said the deal with Cowan had “been in the works for a while,” and that his portfolio would “run the gamut.”
“I think he’s going to be a strategic adviser to every client we have, as needed, and certainly he’ll have his own set of clients,” he said.
Since leaving the Senate, Cowan has steadily cultivated an often arch personality on Twitter, frequently writing about his trademark bowties or with genial exasperation about Congress. On Tuesday, after news broke of his upcoming private sector job, Cowan tweeted, “My 5yr old was tired of seeing daddy laying ’round the house.”Jim O’Sullivan can be reached at Jim.OSullivan@globe.com. Follow him on Twitter at @JOSreports.