A new study finds that nearly 400 House staffers have moved from Capitol Hill to K Street in recent years, suggesting that recent efforts to curb the revolving door between lawmaking and lobbying are having limited effect.

At least 378 of the 5,710 staffers working on the House side of the Hill at the end of 2009 have since left to become registered lobbyists, according to a report from the Sunlight Foundation, a government accountability group.

Corporate America was the biggest beneficiary of this exodus, Sunlight found. Fully 80 percent of the 378 House staffers-turned-lobbyists are working for corporations, industry groups, or Washington lobbying firms with mostly business clients.

On the other hand, nonprofits advocacy groups are only represented by 37 of these recent ex-staffers, the report noted. Only one works directly for a union group, although on K Street some lobbyists have labor clients.

Regardless of which special interest is signing their checks, Sunlight thinks this steady migration from public to private pay is a cause for concern.

“Congress continues to act as a farm team for future lobbyists,” said Lee Drutman, the senior fellow who authored the report released Wednesday. “Staff build up contacts and policy and political experience. Then they often go ‘downtown’ and cash in, taking their expertise and networks with them.”

The 12 members of the deficit-cutting Super Congress might be the most popular people in Washington. As they deliberate how to identify more than $1 trillion in spending cuts, special interests are determined to protect their pet programs — and one way to do so is with campaign contributions.

The committee held a rare public meeting Wednesday, and the debate centered on potential savings from the Defense Department budget, given President Obama’s decision to withdraw all troops from Iraq by year’s end. Any cuts to defense spending won’t sit well with defense contractors like Lockheed Martin and Honeywell, who — among others — have been trying to bullet-proof themselves with campaign contributions.

In just six weeks after the committee members were named, political action committees for almost 100 special interests ponied up more than $300,000 in contributions to the lawmakers. The donations will continue to pour in until the committee has finished its work shortly before Thanksgiving.

Formed as part of a compromise in late July between Republicans and Democrats in Congress, the committee must come up with $1.5 trillion or more in budget savings, enough to match increases in the government's ability to borrow enough money to pay its bills through the beginning of 2013. The whole Congress is required to take an up-or-down vote on the committee’s recommendations by Dec. 23.