Mark Geragos, attorney for Wilkes, served subpoenas to nine Republicans, including Reps. Duncan Hunter of Alpine and Darrell Issa of Vista, and four Democrats. Wilkes made financial contributions to most of them during the period that the now-imprisoned Cunningham admitted taking bribes from Wilkes in return for steering him tens of millions of dollars in defense contracts.

Subpoenas also were issued to former House Speaker Dennis Hastert, R-Ill., House Republican Whip Roy Blunt of Missouri and Democratic Rep. John Murtha of Pennsylvania.

The 13 congressmen who received the subpoenas have sent letters to House Speaker Nancy Pelosi saying that the subpoenas are seeking information protected under the “Speech and Debate” clause of the Constitution, which the courts have interpreted as covering their normal legislative activities.

A congressional source who asked not to be identified said it is likely that the House counsel will ask U.S. District Judge Larry Alan Burns, who is presiding over pretrial proceedings in the Wilkes case, to quash the subpoenas.

“This subpoena is a mystery,” said Issa, who last year donated to charity the $4,000 he identified as contributions from Wilkes' company. “I have no knowledge of information pertaining to the charges pending against Mr. Wilkes that would aid either the defense or the prosecution in this case.”

Hunter, a longtime member of the Armed Services Committee, returned $30,950 he received, directly or indirectly, from Wilkes and from another defense contractor, Mitchell Wade, a former Wilkes associate. Wade pleaded guilty in February 2006 to charges that he provided Cunningham with cash and lavish gifts in exchange for help in getting government contracts.

Washington attorney Stan Brand, who was House counsel from 1976 to 1984, said Geragos' strategy appears to be to assert that the information he is seeking from the congressmen is vital to Wilkes' defense.

“He could say to the judge, 'If you bar me from getting the testimony – then I can't defend my client and you have to dismiss the case.' ” Brand said that under such a scenario, Geragos would probably claim that Wilkes' relationship with Cunningham was not out of the ordinary on Capitol Hill.

Brand said Geragos' strategy appears to be to argue that the congressmen can help establish that Wilkes' relationship with Cunningham was “part and parcel of what was going on” between congressmen and contractors.

A federal grand jury in February charged Wilkes with conspiracy, wire fraud, bribery of a public official and money laundering. It alleged that he provided Cunningham with $700,000 in bribes, including $100,000 in cash in May 2000 and $525,000 in May 2004 to pay off a mortgage. Wilkes also allegedly paid for prostitutes for Cunningham, took the lawmaker on lavish vacations and gave him gifts, including two Sea-Doo Speedster personal watercraft.

The trial is scheduled for Oct. 2 in San Diego.

The other Republicans receiving subpoenas were John Doolittle of Rocklin, Jerry Lewis of Redlands, Peter Hoekstra and Joe Knollenberg of Michigan, and Jerry Weller of Illinois. The other Democrats were Ike Skelton of Missouri, Norm Dicks of Washington and Silvestre Reyes of Texas.