Washington ? Attorney General Alberto Gonzales must quickly clarify apparent contradictions in his testimony about warrantless spying or risk a possible perjury investigation, the chairman of the Senate Judiciary Committee said Sunday.

“This is going to have a devastating effect on law enforcement throughout the country if it’s not cleared up,” said Sen. Patrick Leahy, D-Vt.

“If he doesn’t correct it, then I think that there are so many errors in there that the pressure will lead very, very heavily to whether it’s a special prosecutor, a special counsel, efforts within the Congress.”

Last week, four Democrats on Leahy’s committee asked Solicitor General Paul Clement for the special probe of Gonzales. The request came after FBI Director Robert S. Mueller appeared to contradict Gonzales’ statements to Congress about internal administration dissent over President Bush’s secretive wiretapping program.

Gonzales told that committee the program was not at issue when then-White House counsel Gonzales made a dramatic visit to Attorney General John Ashcroft’s hospital room in 2004. Mueller, before the House Judiciary Committee, said it was.

The apparent contradiction only compounded problems for Gonzales, who is losing support among members of both parties even as he retains Bush’s. The nation’s top law enforcement official has faced growing questions about his credibility and apparent misstatements since Congress began investigating the firings of federal prosecutors seven months ago.

Leahy also said he was ready to work with the Bush administration to modernize a law that governs how intelligence agencies monitor the communications of suspected terrorists.

Bush used his weekly radio address Saturday to urge Congress to update the Foreign Intelligence Surveillance Act of 1978 so the law can better keep pace with the latest technology used by terrorists.

Democrats have indicated they do not want to rush ahead with any changes, seeking to ensure civil liberties are protected and the executive branch is not granted unfettered surveillance powers. But the Bush administration says its latest request is narrowly drawn and urgently needed to stymie terrorist threats.

“The proposal would make clear that court orders are not necessary to effectively collect foreign intelligence about foreign targets overseas,” the national intelligence director, Mike McConnell, wrote congressional leaders Friday. He urged action before Congress departs on a monthlong summer vacation in early August.