Journalist Matt Cooper (search) on Wednesday confirmed to a grand jury that White House aide Karl Rove (search) was his source for a story about a CIA operative that has investigators deciding whether any laws were broken by the leak of the agent's identity.

Cooper told reporters he would give them details of his grand jury testimony — in a future article for Time magazine.

"I'm not going to scoop myself today," Cooper, a White House correspondent for Time magazine, said outside the U.S. District Court Wednesday afternoon.

Cooper spoke after a two-and-a-half hour appearance before the grand jury investigating the leak of CIA officer Valerie Plame's (search) identity. He was one of several journalists to whom Plame's identity was leaked following the publication of an editorial written by her husband, former ambassador Joseph Wilson (search), in which Wilson criticized the Bush administration.

One of those journalists, Judith Miller (search) of The New York Times, is in jail for her refusal to name the person who revealed Plame's identity to her. Last week, Cooper escaped a similar citation for contempt of court when he told the judge his source had waived confidentiality, freeing him to testify before the grand jury.

"Today I testified and agreed to testify solely because of a waiver I received from my source," Cooper said outside the courthouse. "Once a journalist makes a commitment of confidentiality to a source, only the source can end that commitment."

The grand jury is tasked with finding out if whoever leaked Plame's identity to the press two years ago did so with the intent of burning her cover, possibly in retaliation for Wilson's criticisms of the administration's claims that Iraq's nuclear program.

Cooper also said he hoped his testimony would speed up the grand jury's investigation, which would allow Miller to be released from jail. When he announced last week that he planned to testify and would thus be spared from having to go to jail, he proclaimed his solidarity with Miller.

"We should all remember this is Judith Miller's eighth day in jail. The sooner this grand jury recesses, the sooner she can get home," he said Wednesday.

Cooper confirmed that his source on the leak was Deputy Chief of Staff Rove, one of President Bush's most trusted advisers and the man credited with Bush's four consecutive campaign victories.

The waiver that freed Cooper to cooperate with the grand jury was signed by Rove's attorney, Robert Luskin. Cooper's attorney, Richard Sauber, was on hand Wednesday to pass out photocopies of the waiver to reporters.

Cooper also said he would be testifying next week before a Senate committee on a federal shield law for reporters, a measure he supports. Although 49 states plus the District of Columbia have some form of protection for journalists' sources on the books, no federal law governs reporters' privilege.

Earlier, Bush said he would not comment on Rove's role in revealing Plame's identity.

"I have instructed every member of my staff to fully cooperate in this investigation. I also will not prejudge the investigation based on media reports," Bush said at the end of a Cabinet meeting. "Again I will be more than happy to comment on this matter once the investigation is complete."

Rove was present at the meeting, but did not speak.

Last weekend, Newsweek magazine revealed that Rove discussed Plame with Cooper, though Luskin says Rove never gave Plame's name.

In a statement released by the Republican National Committee on Wednesday, Luskin said Rove has testified "fully and completely" on the issue on "several occasions" and has turned over any documents the special prosecutor requested. Rove shared his "full recollection about the brief phone call" from Cooper, which was supposed to be about a story Cooper was preparing on welfare reform.

"Cooper's truthful testimony today will not call into question the accuracy or completeness of anything Rove has previously said to the prosecutor or the grand jury," Luskin said. "ove has cooperated completely with the special prosecutor, and he has been repeatedly assured he is not a target of the investigation. Rove has done nothing wrong. We're confident that he will not become a target after the special prosecutor has reviewed all evidence."

The White House has refused to comment on the matter, to the palpable frustration of the Washington press corps.

Feeling the brunt of the heat is White House spokesman Scott McClellan, who has been hit with sometimes hostile questions from reporters asking what he knows of Rove's role in the leak and whether Rove will be fired if identified as the leaker. Bush had vowed more than once to take action against the person responsible for the leak.

In September and October 2003, McClellan said he had spoken to Rove about the Plame matter and that Rove wasn't involved in the leak. On Wednesday, for the third day in a row, McClellan refused to discuss the denials of two years ago, saying that to do so would impinge on the ongoing criminal investigation of the leak.

Bush ignored a question Tuesday about whether he would fire Rove — his longtime confidant, campaign adviser and now deputy chief of staff — since it was known his adviser did talk to Cooper. But McClellan said later that "any individual who works here at the White House has the confidence of the president."

The leak case is problematic for the administration on two fronts. First, is the question of whether Rove, or another administration official, broke the law in revealing Plame's identity. The 1982 Intelligence Identities Protection Act makes it a crime to knowingly reveal an undercover agent. Only one person has ever been convicted of violating the act.

Second, is the political problem of keeping on a staffer at the center of a scandal. Even before Rove helped Bush to his first major victory over Democratic superstar and former Texas Gov. Ann Richards in 1994, he was a trusted consultant to President George H.W. Bush. The Bush clan is known for prizing loyalty; turning Rove out of the administration would be a hurt felt both professionally and personally.

So far, the Bushes are sticking by Rove, while Democrats are calling for his ouster. Some Democratic senators are also seeking a new investigation from White House Chief of Staff Andrew Card, claiming the current probe failed.

"The bottom line is clearly Mr. Rove was involved," said Sen. Chuck Schumer, D-N.Y., "The American people deserve answers ... if the leak was an act of retribution, it was a dastardly act."

Democratic members of the House Intellligence Committee asked Bush on Wednesday to suspend Rove's security clearances.

"We abhor the disclosure of the identities of undercover officers," wrote all the Democratic members of the committee, led by ranking member Rep. Jane Harman. They cited another letter signed by 10 former intellegience officers calling the leak of Plame's identity a "shameful and unprecedented event in American history."

But Republicans said Democrats and others have no basis for outrage over Rove's actions.

"This is typical of Democrats. They smell blood and they act like sharks," House Majority Leader Tom DeLay told FOX News. "Karl Rove is a good man. He was doing his job ... I don't see that he has done anything wrong."

Rove's conversation with Cooper took place five days after Plame's husband suggested in a New York Times op-ed piece that some of the intelligence related to Iraq's nuclear weapons program was twisted to exaggerate the Iraqi threat.

Eight days after the op-ed piece, Plame's name and her connection to the CIA first appeared in a newspaper column by Robert Novak (search).

The column said two administration officials told Novak that Wilson's wife had suggested sending him to investigate whether Iraq had tried to obtain uranium from Niger. Cooper's byline appeared on an article a few days later naming Plame.

An e-mail by Cooper that was reported in Newsweek magazine said Rove spoke of the wife of former U.S. Ambassador Joe Wilson as being someone who apparently works at the CIA and who arranged a trip for her husband to Africa.

Cooper's e-mail said Rove warned him away from the idea that Wilson's trip had been authorized by CIA Director George Tenet or Vice President Dick Cheney.

"He gave proper guidance to a reporter who got disinformation in a leak" meant to assign responsibility to Cheney, former Bush aide Ed Rogers told FOX News.

RNC chairman Ken Mehlman said Rove "was discouraging a reporter from writing a false story based on a false premise."

Democrats say Luskin's insistence that Rove never actually used Plame's name is nothing more than an attempt to parse Rove's comments. Legal experts agree that Rove did not have to mention Plame by name to have violated the law.

On Wednesday, House Minority Leader Nancy Pelosi of California repeated Democratic calls for Rove to be fired.

"Whether it's a criminal offense or not, it's an act against the national security of the United States. No person who has divulged the name of a CIA covert operative should be in the employ of the U.S. government. It's up to the special prosecutor to find out whether that person should also be indicted in addition to being fired. So yes, I think he should be fired," Pelosi said.

FOX News' Jane Roh and The Associated Press contributed to this report.