A limousine company linked to a congressional bribery scandal has sued the Department of Homeland Security, claiming the agency caved to political pressure by trying to shut the company out of contracts.

In a lawsuit in the U.S. Court of Federal Claims, Shirlington Limousine of Arlington, Va., alleged that Homeland officials sought bids on a transportation contract last fall in a manner designed to keep Shirlington from competing so as to "relieve some of the political pressure" from members of Congress.

Homeland spokesman Larry Orluskie refused comment on the lawsuit, but said the agency's contracting decisions have nothing to do with any one company.

"Bottom line is this is about getting the best deal for the American taxpayer, it's about economy of scale," Orluskie said.

The litigation comes after Shirlington surfaced as a minor player last year in the scandal that sent former Republican Rep. Randy "Duke" Cunningham of California to prison for taking more than $2.4 million in bribes from defense contractors.

Shirlington Limousine president Christopher Baker appeared before a grand jury in San Diego as investigators sought to determine whether a contractor had provided Cunningham with prostitutes and limos. Neither the company nor Baker were ultimately named in indictments in the case, and prosecutors didn't end up raising accusations of prostitution in the D.C. area.

Shirlington featured in several angry congressional hearings last summer about why it was able to get contracts with Homeland despite a history of problems including poor service on other contracts and Baker's criminal record.

Lawmakers discovered that Cunningham had written a letter to DHS recommending Shirlington for contracts, though DHS said it misplaced the letter and asserted Cunningham's intervention had nothing to do with two contracts Shirlington got in 2004 and 2005, totaling about $25 million, to ferry DHS employees around the D.C. area.

At about the time of the hearings, the Department of Homeland Security decided to redo its transportation contracts. The request for proposals it issued in November didn't include a certain set-aside for small businesses that Shirlington had pursued in the past. Orluskie said that set-aside was no longer practical but that Shirlington could have bid on the contract anyway.

Shirlington claims that Homeland officials violated the law by not restricting competition to certain small businesses, and also contends that the company went to great lengths to submit its proposal on time but was foiled by convoluted procedures.

Because Cunningham had used Shirlington sedans, Baker "was dragged by the press 'feeding frenzy' into the fray. He was never charged with any wrongdoing whatsoever," says Shirlington's lawsuit, which cites complaints by lawmakers.

The government has not yet filed its response.

Shirlington's lawsuit was first reported Wednesday by The Hill newspaper.