"Al was right. Mistakes were made and he's going up to Capitol Hill to correct them," Bush said at a press conference in Mexico with Mexican President Felipe Calderon. "I appreciate the fact that he's taking some action."
Bush said he spoke with Gonzales by phone Wednesday morning about the need for the attorney general to explain the Justice Department's decision to lawmakers.
"The fact that both Republicans and Democrats feel like that there was not straightforward communication troubles me and it troubles the attorney general," Bush said.
• FOX Fan Speakout: Do you think the White House or the Attorney General acted innappropriately in firing eight U.S. attorneys?
The president said he's received complaints about U.S. attorneys and it's common practice for presidents to remove them, saying the firings were "entirely appropriate."
"U.S. attorneys serve at the pleasure of the president. In other words, they are appointed by the president, they can be removed by the president," Bush added.
In response to repeated calls for his resignation, Gonzales left whether he stays at the Justice Department up to Bush, saying "that's the decision for the president to make." Bush said he has confidence in Gonzales and he will take action to address the situation.
One day after he took responsibility for mistakes made in the firings of eight U.S. attorneys, Gonzales told FOX News: "I am focused on looking to see what happened here in this particular case with respect to these U.S. attorneys and making sure that doesn't happen again, making sure that Congress understands what happened."
The vast majority of those calling for Gonzales' ouster have been Democrats, but they were joined late Wednesday by the first Republican to do so, Sen. John Sununu of New Hampshire, who is expected to face a tough re-election battle next year.
"The president should fire the attorney general and replace him as soon as possible with someone who can provide strong, aggressive leadership prosecuting the war on terrorism, running the Department of Justice, and working with the president and Congress on important homeland security matters," Sununu said, according to a statement released by his office.
Senate Majority Leader Harry Reid joined a growing list of Democrats calling for Gonzales to resign. Others include presidential hopefuls Sen. Hillary Clinton and John Edwards.
“It's wrong, it’s unethical, it’s immoral. I believe it’s criminal. And Gonzales should be fired,” Reid said.
Democrats want to question top White House officials immediately, and sent letters to Deputy Chief of Staff Karl Rove, former White House counsel Harriet Miers and deputy White House counsel William Kelley late Tuesday to appear before lawmakers.
"We would like to work out a process for you to make yourself available to the committee for interviews, depositions, or hearing testimony, on a voluntary basis, and to produce documents in your possession, control, or custody related to our investigation," according to the letter sent to Rove.
White House counsel Fred Fielding held a closed door meeting with key House and Senate Judiciary Committee members on Wednesday. Sen. Charles Schumer, D-N.Y., said lawmakers told Fielding they wanted to hear from Rove, Miers, Rove's deputy and Miers' former deputy.
Fielding said the White House would respond by Friday, Schumer added.
“We hope to get answers,” Schumer told reporters on Capitol Hill.
If they refuse to testify, lawmakers say they might consider issuing subpoenas. Sens. Patrick Leahy, D-Vt., and Arlen Specter, R-Pa., sent letters asking for cooperation with the Senate Judiciary Committee's investigation of the firings.
Critics say some of the attorneys fired were pressured by Republicans to address investigations of potential voter fraud involving Democrats.
Reasons behind the firings were not improper, Gonzales said.
“These decisions were not based upon retaliation from cases brought or not brought. The decisions were not based on trying to interfere with an ongoing public corruption case. Here there was simply dissatisfaction, a desire to see if we could make improvements in the performance of these districts,” Gonzales said.
Gonzales' chief of staff, Kyle Sampson, who announced his resignation on Tuesday, discussed the possible firings in early 2005 with Miers, according to e-mails. Miers left the administration earlier this year.
Gonzales, himself a former White House counsel, has been friends with Bush for years, going back to when he served as Bush's secretary of state in Texas; Bush was then the governor of that state.
The U.S. attorneys, the chief federal law enforcement officials in their districts, typically are appointed to four-year terms by the president on the recommendation of state political leaders, but — like the attorney general and other Cabinet officers — they serve at the pleasure of the president and can be dismissed at any time.
When the party in power changes hands in the White House, it is expected that the new president will fire all the sitting U.S. attorneys, as was the case for both Ronald Reagan in 1981 and Bill Clinton in 1993. President Bush, unlike Clinton and Reagan, did not fire all the attorneys en masse when he took office in 2001, and allowed a few to continue in their positions for several months. All were replaced with his own selections early in his administration, however.
It is very unusual for a president to fire U.S. attorneys who were his choices for the job.
It was the second time in as many weeks that Gonzales came under withering criticism on Capitol Hill.
Last week, the attorney general and FBI Director Robert Mueller admitted that the FBI had improperly, and at times illegally, used the USA Patriot Act to secretly pry out personal information about Americans in terrorism investigations.
As for the firings, Bush spokesman Bartlett said White House officials had heard complaints from members of Congress regarding prosecutors and Bush had raised the subject during an October 2006 meeting with Gonzales. He described the exchange as "offhand" and said Bush did not name any specific prosecutors but did identify their states.
"This briefly came up and the president said, 'I've been hearing about this election fraud issue from members of Congress and want to be sure you're on top of it as well,' " Bartlett said.
Bartlett said that Gonzales had responded, "I know, and we're looking at those issues."
FOX News' Steve Centanni, Trish Turner and The Associated Press contributed to this report.