Vice President Dick Cheney's office acknowledged it has documents that "may be responsive" to an investigation into a secret eavesdropping program, although it indicated it would not turn over the papers without a fight.

Lawyers speaking on behalf of both President Bush and Cheney asked the Senate Judiciary Committee Monday for more time to respond to subpoenas involving a wiretapping program that Democrats in Congress have harshly questioned.

In a letter to committee Chairman Patrick Leahy, Cheney's counsel Shannen W. Coffin, reported that the vice president's office had identified more than 40 "Top Secret/Codeword Presidential Authorizations" and memoranda from the Justice Department that may respond to the subpoena.

The documents listed in the letter are dated from Oct. 4, 2001 — about a month after the Sept. 11 terror attacks — and December 2006.

"We continue our efforts to identify further documents that may be responsive to the subpoena and renew the request made in our letter of Aug. 10, 2007 for an extension of time," Coffin wrote.

Cheney's counsel, however, did not indicate whether the vice president's office was willing to hand the documents without a struggle. The letter did indicate that Cheney would follow the lead of the president if Bush decided to assert executive privilege in refusing to turn over documents.

Leahy was not happy with the administration's response, threatening to hold key officials in contempt for not producing subpoenaed information about the legal justification for the eavesdropping program.

"When the Senate comes back in the session, I'll bring it up before the committee," the Vermont Democrat said. "I prefer cooperation to contempt. Right now, there's no question that they are in contempt of the valid order of the Congress."

Leahy's committee on June 27 subpoenaed the Justice Department, National Security Council and the offices of the president and vice president for documents relating to the National Security Agency's legal justification for the wiretapping program.

White House lawyer Fred Fielding, in a separate letter to Leahy, said the administration needed more time.

"A core set of highly sensitive national security and related documents we have so far identified are potentially subject to claims of executive privilege and that a more complete collection and review of all materials responsive to the subpoenas will require additional time," Fielding said.

Congress, before it left for its August recess, approved an update to the 1978 Foreign Intelligence Surveillance Act, allowing the government to eavesdrop on terror suspects overseas without first getting a court warrant.

The overhaul was the result of a recent Foreign Intelligence Surveillance Court ruling that banned eavesdropping on foreigners when their messages were routed though communications carriers based in the United States.

The provisions expire after six months, but the White House wants them made permanent.

"For Congress to legislate effectively in this area, it has to have full information about the executive branch's interpretations of FISA," Leahy said. "We cannot, and certainly, we should not legislate in the dark, where the administration hides behind a fictitious veil of secrecy."