Need evidence that partisan rancor thrives on Capitol Hill? Then how about “chicken crap”? That’s what Speaker-designate John Boehner (R-Ohio) called House Democrats’ tax bill last week.

But even as Members of Congress are reveling in scorching partisan rhetoric, collegiality among Republicans and Democrats still flourishes in one Washington, D.C., enclave: K Street, the very sector that gets blamed for many of the city’s ills.

“It’s a war zone up there on the Hill,” said lobbyist and former Sen. John Breaux (D-La.), who is in business with ex-Sen. Trent Lott (R-Miss.). “There’s no war zone downtown.”

That’s because on K Street, Democrats and Republicans are paid to work for the same thing: their clients’ interest. True, corporate lobbyists don’t hide their party affiliations when they go to the private sector. They continue to raise money and promote their favored candidates on their own time. They often take the lead in reaching out to Members of their party on the behalf of clients. And, of course, some lobbyists benefit from the gridlock and partisan vitriol on the Hill when their goal is to kill a bill.

But even the most partisan K Streeters log hours a day on conference calls or in meetings with bipartisan teams of lobbyists. It’s hard not to find a work buddy, or even a friend, who votes a different way.

Breaux, a moderate Member who was known for working with colleagues from both parties, said that at his lobbying firm, Patton Boggs, Republicans and Democrats intermingle.

“There’s not a Republican floor or a Democratic floor; everybody is all over the place and working together,” he said. “We get to know the personal side of each other. That’s missing in the Congress.”

Just why that’s missing on the Hill and for how long it’s been gone remain topics of great debate inside and outside of Congress.

Breaux has a theory to offer: More Members ditch D.C. on the weekends, so their families don’t do things together socially. Another reason, he said, is “the advent of the PR people that run campaigns who have convinced you that the only way you can win is by destroying your opponents.”

Lobbyists, no matter their party affiliation, must take a more pragmatic, deal-brokering approach to get a win for their clients. And theoretically, once elected, Members also have a unifying cause: working on behalf of the country.

“We share notes and develop strategies,” Breaux said of his fellow lobbyists. “I wish they did more of that in the Congress itself. I think that’s what the American people want.”

Democratic lobbyist Andy Rosenberg agreed.

“I gave myself a New Year’s resolution to put together a group of lobbyists from both parties who are thoughtful, constructive, reasonable people,” said Rosenberg, a partner with the bipartisan boutique Thorn Run Partners. “Lobbyists, by and large, not only have a stake in but believe in our government, and it’s harmful when Democrats and Republicans are extremely negative on each other.”

Rosenberg’s business partner, Republican Chris Lamond, said the state of bipartisanship on Capitol Hill is grim. Downtown, being in a bipartisan firm offers protection from the whims of elections.

“Andy and I are polar opposites in politics, but we think alike when it comes to running the business,” Lamond said.

Rosenberg added that Capitol Hill could learn something from the lobbying set, whose ultimate goal is to get people from different parties to achieve a common objective.

“In terms of looking around this country, where do Republicans and Democrats actually work well together to get things accomplished and to find compromise? You’d be hard-pressed to find a more collaborative place than on K Street,” he said.

“That’s what’s missing on Capitol Hill,” Rosenberg added. “That’s why there’s so much widespread dissatisfaction. They are not encouraged to be pragmatic; they are encouraged to be ideological.”

But it is the lobbyists who sometimes push Members to dig in their heels on controversial issues, so perhaps K Street shares a little of the blame.

Rosenberg and most corporate lobbyists say they’re not the problem.

“That sort of lack of collaboration in Washington actually is driven by the ideological interest groups — the tea party or MoveOn.org — extremists that really don’t want any compromise,” he said. “Lobbyists, by our very nature, are all about the art of the deal.”

Of course, sometimes they’re not.

Sometimes it’s simply about stopping measures outright. But even then, most K Streeters say they typically look for Congressional allies on both sides of the aisle to mobilize against a bill or an amendment.

On the Hill, policy does sometimes trump politics, but usually it’s the other way. Lobbyists say they don’t know how the already-looming 2012 elections will factor into the partisanship in the House and Senate. Some Democratic Senators, for example, are striking a moderate tone when it comes to earmark reform. But GOPers in both chambers may worry about linking up with Democrats for fear of being characterized as not conservative enough. That could open them up to potential primary challenges. 

What business advocates do take from all this political uncertainty is that it’s safer to be bipartisan because there could be a lot of flip-flopping over the next few election cycles.

“If a client walks in the door to a firm like ours, I can’t control who his Congressmen or Senators are, so we have to work with both Democrats and Republicans on the Hill,” said Michael Herson, a Republican who is president of American Defense International. “And I have great Democratic lobbyist friends that I work with or sometimes refer business to.”

Richard Hunt, president of the Consumer Bankers Association, said it’s just easier to push an issue by collaborating with lobbyists from both parties.

“We’ve all seen in the K Street community, it’s great to have a couple of Democrats and Republicans together on an issue,” said Hunt, former chief of staff to then-Rep. Jim McCrery (R-La.). But no matter their partisan ties, it’s important to retain lobbyists that “believe in your cause, in your industry,” Hunt said.