WASHINGTON (CNN) -- The Bush administration's anti-terrorist surveillance efforts are more extensive than top officials have acknowledged, going beyond the controversial no-warrant eavesdropping program, the U.S. intelligence chief said Tuesday.
Attorney General Alberto Gonzales is being asked to provide records about a data-mining program.
President Bush acknowledged a program allowing the government to wiretap phone calls without obtaining a warrant in 2005. The program, run by the National Security Agency, is at the center of disputed congressional testimony by Attorney General Alberto Gonzales.
Gonzales is defending himself against allegations that he lied to Congress about a 2004 dispute between the White House and Justice Department over the legality of the eavesdropping program.
In a letter defending the embattled attorney general, National Intelligence Director Mike McConnell states that eavesdropping is just one of the programs President Bush authorized after the September 11, 2001, attacks on New York and Washington.
"This is the only aspect of the NSA activities that can be discussed publicly because it is the only aspect of those various activities whose existence has been fully acknowledged," McConnell wrote.
The letter was requested by Sen. Arlen Specter, the ranking Republican on the Senate Judiciary Committee, in order to clarify the accuracy of Gonzales' testimony.
Specter told CNN's "The Situation Room" that McConnell's letter will require further interpretation once he receives an accompanying letter from Gonzales.
"If he doesn't have a plausible explanation, then he hasn't leveled with the committee," Specter said.
Bush acknowledged the no-warrant eavesdropping program's existence in December 2005, after it was disclosed in The New York Times. He insisted the program -- which targets communications into and out of the United States by people suspected of having ties to the al Qaeda terrorist network -- was legal and carefully reviewed.
Critics say the program violates a 1978 law that requires the approval of a special court that oversees wiretaps in intelligence cases.
Bush called the disclosure of the surveillance program "a shameful act" and added, "The fact that we're discussing this program is helping the enemy."
In 2006, Gonzales told a Senate committee there was no "serious disagreement" over the surveillance program within the administration. But former Deputy Attorney General James Comey testified in May that he and other top Justice officials were prepared to resign in 2004 if the program were re-authorized, describing a dramatic nighttime standoff with Gonzales -- then White House counsel -- in former Attorney General John Ashcroft's hospital room over the matter.
Gonzales told Congress last week that the dispute was over "other intelligence activities," not the eavesdropping program. Gonzales will lean heavily on this distinction as he defends himself against perjury charges. Watch how Gonzales may defend himself »
But FBI Director Robert Mueller testified last week that Ashcroft told him it did involve the program.
However, a former government official familiar with the controversy told CNN over the weekend that the dispute centered not on eavesdropping, but on data-mining -- running computer searches through electronic databases that identified the senders and recipients of the e-mails or calls intercepted.
Democrats, however, say it doesn't matter because the data-mining project was a facet of the NSA eavesdropping program. Also, the former government official who confirmed the existence of the data-mining program has said Gonzales "may have been splitting hairs."
The Bush administration has remained mum on whether it authorized data-mining.
In a Monday letter, Rep. John Conyers, chairman of the House Judiciary Committee, asked Gonzales to hand over "all opinions, memoranda and background materials, as well as any dissenting views, materials and opinions" about the data-mining program.
Conyers questioned whether that aspect of the surveillance program was leaked "to rehabilitate previous controversial testimony by you." Conyers further said that the Judiciary Committee wants to know if the Justice Department knew about the leaks or authorized them.
Gonzales' disputed statements -- coupled with an ongoing controversy over the allegedly political dismissals of eight U.S. attorneys last year -- have sparked bipartisan calls for the attorney general's resignation or ouster.
On Tuesday, a group of congressmen announced they had introduced a resolution calling for an investigation to determine whether the attorney general should be impeached.
The White House insists Gonzales testified truthfully and restated Bush's support for his longtime aide, with spokesman Tony Snow telling reporters that Gonzales could not speak directly to classified matters in an open hearing.
"As members have an opportunity to examine fully what's going on, we hope that they will sit around and make reasoned judgments rather than leaping to theatrics," Snow said.
Vice President Dick Cheney also has defended Gonzales.
"I think Al has done a good job under difficult circumstances," Cheney told CBS Radio on Monday. "The debate between he and the Senate is something they're going to have to resolve, but I think he has testified truthfully."
Cheney said he disagreed with Specter, who called Sunday for Gonzales to step down.
"I think the key is whether or not [Gonzales] has the confidence of the president, and he clearly does," Cheney said.
On Tuesday, Cheney continued his defense of Gonzales, saying that he stood by him and held him "in high regard."
"With respect to the U.S. attorneys, there has been, I think, a bit of a witch hunt on Capitol Hill as they keep rolling over rocks hoping they can find something, but there really hasn't been anything that has come up to suggest that there was any wrongdoing on any kind," Cheney said. E-mail to a friend