After a decade of Republican efforts to clear Democrats from K Street, a voice of support for Democratic lobbyists is emerging from an unlikely source: their Republican colleagues.

Though Republicans reclaimed the White House and expanded their majorities in Congress in the November elections, Republican lobbyists, somewhat counterintuitively, say their Democratic counterparts remain relevant, and valuable.

“If anybody feels they can get things done with just Republicans, they’re making a mistake,” said ex-Rep. Bob Livingston (R-La.), a former chairman of the House Appropriations Committee and founder of the Livingston Group, a bipartisan firm.

Indeed, partners at many all-GOP firms said they will continue to work closely with Democratic lobbyists at other firms, recommending clients or subcontracting to them.

Some have even upended their business model by hiring Democrats.

The firm formerly known as Mehlman & Vogel, founded less than a year ago by two high fliers with strong ties to the Bush administration, announced earlier this month that it was adding David Castagnetti, a veteran of the Kerry-Edwards campaign, as a name partner.

Alex Vogel said he wasn’t shopping for a Democrat, but conceded that by hiring one, the firm “expands our ability to reach out and serve our clients.”

Heads of the all-Republican lobbying shop the Navigators are thinking about following suit.

“It’s something we’re discussing right now,” said Cesar Conda, a former top aide to Vice President Cheney. “This is still an all-Republican town, but in the Senate, you have to be able to reach both sides.”

But why now?

Many lobbyists at all-GOP shops said that as Republicans have grown more confident in their degree of control in Washington, they now feel free to reach across the aisle — a move they think will benefit business.

They said their clients understand that while Democratic power is clearly diminished, the minority party will continue to count in the Senate, where Republicans still lack a 60-seat filibuster-proof majority. On issues such as energy and telecommunications, votes can split along regional, rather than partisan, lines.

In addition, some clients feel more comfortable maintaining ties to Democrats either because they may retake power at some point in the future, or because they don’t want to alienate customers or suppliers who may be Democratic.

To be sure, all-GOP firms have done robust business recently, and most partners at those firms said they expect their growth to continue. Last year, for example, the major all-Republican firms saw their revenue jump by nearly 50 percent, while Washington’s 25 biggest lobbying firms — primarily a bipartisan lot — experienced only 8 percent growth.

Republican wins at the polls seem to be bolstering those trends.

Many officials with GOP-heavy firms reported getting flooded with calls from prospective clients before the ink on the post-election newspapers was dry.

But those lobbyists pointed to their hustle and ability — rather than their Republican stripes — as the prime engines driving their firms’ growth. Most said they actually risk sacrificing business by remaining partisan.

For the Navigators, a firm now less than two years old, the decision to stay Republican has cost a couple of potential clients who wanted access to Senate Democrats. So now, Conda said, partners are considering adding at least one Democrat to their roster.

Lobbyists at other partisan shops acknowledged that their firms’ makeup has caused them to miss out on some potential business. For some of those firms, a solution lies not in bringing Democrats in, but in outsourcing a client’s Democratic lobbying needs to Democrats at other firms.

The all-GOP Alexander Strategy Group, for example, has been so closely linked with the all-Democratic Harbour Group that the two firms share office space.

Another lobbyist in an all Republican firm said he often refers clients to Democratic lobbyists at other firms, who often attend weekly meetings with them.

The lobbyist said in those meetings, his Democratic counterparts offer a needed sense of perspective.

“I may suggest something that would put the client in good position with the administration but would put them in a bad position with an important Democrat on a committee,” he said. “So you need to have both firms represented in the room to harmonize all that stuff out.”

The Republican lobbyist makes clear that his willingness to work with outside Democrats should not be interpreted as a sign he is ready to water down the partisan bona fides of his firm.

“There have been times when we have missed the chance to have a new client because the client really felt they needed to work with a bipartisan firm,” he said. “But that’s OK. We’re willing to forgo some opportunities for the sake of building a strong Republican company.”

For their part, Republican lobbyists at bipartisan firms say they can be just as loyal soldiers to the cause while working alongside Democrats.

“Some Republican-only lobbyists say Republicans on the Hill trust them more, but I just don’t buy that argument,” said T.J. Petrizzo, a co-founder of the bipartisan firm Bockorny Petrizzo. “Based on the work Dave [Bockorny, a Democratic name partner] and I have done, I’m pretty confident we have their trust.”

Indeed, Petrizzo’s firm is predominantly Republican, and Republican lobbyists there held fundraisers for every major Senate contender this year.

The firm’s Democrats did the same for their candidates.

“Whether you’re a Democrat or a Republican, I want you to be partisan, because it benefits our firm,” Petrizzo said. “It makes good business sense because it’s what’s best for our clients.”

Some Republicans at bipartisan firms are less accommodating.

Former Rep. Bill Paxon (R-N.Y.) was hired by Akin, Gump, Strauss, Hauer & Feld LLP in 1998 to trailblaze for Republicans in that firm’s traditionally Democratic lobbying operation.

Asked if he would be willing to hire a Democrat, Paxon replied that his focus is “on bringing on Republicans.”

“I was very involved in expanding the Republican presence here, and I always want to hire more,” he said.

Paxon has been an architect of the vaunted K Street Project, a two-year-old GOP effort to promote Republicans in the lobbying business at the expense of Democrats.

Democratic lobbyists have elevated the project to mythic heights of conspiracy, and while most acknowledge that the program’s reputation exceeds its reach, they also concede that as a tactic to scare trade associations and potential clients, it has largely been successful.

For Democratic lobbyist Paul Equale, the threat was real: He was one of the project’s first victims in 2001, when he was edged out as head of the Independent Insurance Agents of America.

Equale, who since has hung out his own shingle and now focuses on consulting, said that Republicans will likely keep their edge on K Street as long as they dominate elected offices.

But he added that, as a long-term model, a bipartisan firm hedges its bets more effectively.

“I’ve long believed it takes two wings to make an airplane fly,” he said.