Four longtime senators recently announced their retirements from the Senate effective at the end of 2012. This independent living in santa clara could send ripples through K Street as a number of lobbyists will lose the chief contact they had to Capitol Hill, their former boss. Sens. Jon Kyl, Joe Lieberman, Kent Conrad, and Kay Bailey Hutchison have a combined 51 former staffers turned lobbyists who may see their bottom line suffer when their former boss steps down.

A recent study from the Centre for Economic Performance showed that a lobbyist who previously worked for a senior senator takes an average revenue loss of 24 percent when their former boss leaves office. Those who worked for junior senators saw negligible revenue loss when their former boss left office. The study also found that former staffers who worked for senators with positions on the most powerful committees, Appropriations and Finance, suffered even bigger losses in revenue with the departure of their former boss.

Three of the four departing senators, Conrad, Lieberman, and Hutchison, were the senior senators for their state. Three also held seats on the key committees, Conrad and Kyl on Finance and Hutchison on Appropriations. Additional important posts include Kyl’s post as Republican Minority Whip and Lieberman’s chairmanship of Homeland Security & Government Reform.

Some of the former staffers turned lobbyists for these departing senators may avoid this expected loss in revenue due to previous work in other government jobs or due to their departure from the soon-to-be former senators occurring decades ago. Others who left Congress for K Street more recently are likely to take a hit.

One lobbyist exemplifying the imminent loss in revenue would be Alberto Cardenas of the firm Vinson & Elkins. Cardenas worked for Sen. Kay Bailey Hutchison from 2005 to 2009. Most of Cardenas’ clients are local Texas entities, the Greater Houston Partnership or the Texas Public Hospital Coalition, seeking government contracts that Sen. Hutchison could provide from her perch on the Appropriations Committee.

Former staffers for Sen. Kent Conrad have a number of clients with interests directly related to the senator’s position on the Finance Committee. Robert Van Heuvelen runs his own lobbying firm and boasts a series of clients from the health and energy sectors, both of which sought to influence the Finance Committee’s work on health care reform and climate change legislation. Van Heuvelen also employs former Conrad staffer Anissa Rogness. Another former Conrad staffer, Lindsey Toohey, held a cross-section of important health care organizations as clients in 2010. With Conrad’s departure from the Senate, these lobbyists could see their stature fall in the coming years.

Sen. Joe Lieberman has long been known as a friend to the defense industry and a few of his former staffers turned lobbyists may suffer because of it. Both Steve Sutton and Fred Downey work in the aerospace industry with Sutton representing Northrop Grumman and Downey representing the Aerospace Industries Association of America.

These lobbyists may be looking at a break-up season with some of their clients in the near future. Lobbying clients are always looking for the relevant connections in the resume of their hired guns. Those with used-up connections are free to leave on the sidelines.