They asked Clement to immediately appoint an indepedent counsel from outside the Justice Department to determine whether Gonzales "may have misled Congress or perjured himself in testimony before Congress."
A draft copy of the letter was obtained by The Associated Press shortly before a news conference planned by the senators.
Neither Gonzales nor the Justice Department had immediate comment about the letter. A spokesman for Senate Majority Leader Harry Reid, D-Nev., said he supports the request.
Senate Judiciary Chairman Patrick Leahy of Vermont, in a separate letter Thursday to Gonzales, said he would give the attorney general eight days to correct, clarify or otherwise change his testimony "so that, consistent with your oath, they are the whole truth."
The four senators said that Gonzales' testimony last year that there had been no internal dissent over the president's warrantless wiretapping program conflicted with testimony by former Deputy Attorney General James Comey and with Gonzales' own statements this week before the Judiciary Committee.
They also said Gonzales falsely told the panel that he had not talked about the firings with other Justice Department officials. His former White House liaison, Monica Goodling, told the House Judiciary Committee under a grant of immunity that she had an "uncomfortable" conversation with Gonzales in which he outlined his recollection of what happened and asked her for her reaction.
"The attorney general should be held to the highest ethical standards," the senators wrote.
Yes, the chief law enforcement officer in the land should absolutely be held to the highest of ethical standards. Unfortunately, when we are talking about the Bush Organized Crime Syndicate; that ideal just doesn’t mean the same thing as it does to you and me (presuming you view the Rule of Law and the Social Contract as more than mere technicalities.)