On the heels of major departures at Ogilvy Government Relations in the final days of last year, two more lobbyists are leaving to launch their own K Street shop. Democrat Andy Rosenberg and Republican Chris Lamond are setting up Thorn Run Partners this week.

“We want to build a firm of experienced senior-level people who will service clients,— said Rosenberg, a one-time aide to the late Sen. Edward Kennedy (D-Mass.) and a former lobbyist at Patton Boggs. “Chris and I certainly aren’t putting any limits on how fast or big we’re going to grow.—

Lamond, a former aide to then-Sen. Fred Thompson (R-Tenn.), said the new firm has no timetable for adding new lobbyists. “It’s all about finding the right fit,— he said. “It could be immediate.—

Thorn Run, named for Rosenberg’s West Virginia farm, is launching with more than a dozen clients, many of which are health care interests, including Millennium Pharmaceuticals, the Medical Device Manufacturers Association, Inverness Medical Innovations and Universal Health Care Group as well as non-health-care clients such as the International Packaged Ice Association and Affiliated Computer Services Inc.

At the end of last year, Ogilvy Government Relations announced that Stewart Hall, John Green and Jim Baker were leaving the operation. Gordon Taylor, a former aide to then-Rep. Chris John (D-La.), has taken over as president, while Drew Maloney, a longtime Republican lobbyist, is taking over as CEO. Republican Wayne Berman and Democrat Moses Mercado are serving as co-chairmen of Ogilvy, the firm announced in December.

Lamond and Rosenberg say their departures are not related to the changes at their former firm.

“Our decision has nothing to do with what’s happening at Ogilvy,— Rosenberg said. Ogilvy “has a lot of strong people who we’re still friendly with.— Lamond added, “Andy and I had independently thought about setting up our own shops. It was a goal we’d had, and it turned out that 2010 was a good time to do it.—

Rosenberg and Lamond have worked together since 2005 when Rosenberg became the first Democrat to work at the all-GOP Federalist Group, which was sold later that year to Ogilvy and adopted the corporate parent’s name. The buyout of the firm was reportedly completed at the end of last year, explaining some of the turnover at the shop.

Rosenberg, who previously made an unsuccessful run for the Congressional seat held by Rep. Jim Moran (D-Va.), said he and Lamond will remain politically active. “In a smaller firm, you have to even turn it up a notch,— Rosenberg said.

Even so, Lamond and Rosenberg said they had little question about making their firm bipartisan. “We are very passionate about our own politics, and we don’t agree on a lot politically,— said Rosenberg, who was a co-founder of the Draft Obama effort (before Obama banned donations from federal lobbyists). “But we share an appreciation for how to provide a service for clients and how to practice our trade.—