Updated: 2007-08-27 21:25

This is a file picture of US Attorney General Alberto Gonzales in Washington on July 24, 2007. [AP]

US Attorney General Alberto Gonzales resigned, officials said Monday, ending a monthslong standoff with critics who questioned his honesty and competence at the helm of the Justice Department.

Republicans and Democrats alike had demanded his resignation over the botched handling of FBI terror investigations and the firings of US attorneys, but President Bush had defiantly stood by his Texas friend until accepting his resignation Friday, according to senior US administration officials who spoke on condition of anonymity.

The Justice Department planned a news conference for 10:30 am EDT, in Washington. Bush planned to discuss Gonzales' departure at his Crawford, Texas, ranch shortly thereafter.

Solicitor General Paul Clement will be acting attorney general until a replacement is found, said the officials who spoke on condition of anonymity to avoid pre-empting the announcement.

Homeland Security chief Michael Chertoff was among those mentioned as possible successors. However, a senior administration official said the matter had not been raised with Chertoff. Bush leaves Washington next Monday for Australia, and Gonzales' replacement might not be named by then, the official said.

"Better late than never," said Democratic presidential candidate John Edwards, summing up the response of many in Washington to Gonzales' resignation.

Gonzales served more than two years as the nation's first Hispanic attorney general.

Bush steadfastly -- and at times angrily -- refused to give in to critics, even from his own GOP, who argued that Gonzales should go. Earlier this month at a news conference, the US president grew irritated when asked about accountability in his administration and turned the tables on the Democratic Congress.

"Implicit in your questions is that Al Gonzales did something wrong. I haven't seen Congress say he's done anything wrong," Bush said testily.

Gonzales, 52, called Bush on Friday to inform him of his resignation, according to a senior administration official who spoke on condition of anonymity to not pre-empt Gonzales' statement. The president had Gonzales come to lunch at his ranch on Sunday as a parting gesture.

Gonzales, whom Bush once considered for appointment to the Supreme Court, is the fourth top-ranking administration official to leave since November 2006. Donald H. Rumsfeld, an architect of the Iraq war, resigned as defense secretary one day after the November elections. Paul Wolfowitz agreed in May to step down as president of the World Bank after an ethics inquiry. And top Bush adviser Karl Rove earlier this month announced that he was stepping down.

Reacting to Monday's developments, Senate Judiciary Committee Chairman Patrick Leahy, D-Vt., said that Gonzales' department had "suffered a severe crisis of leadership that allowed our justice system to be corrupted by political influence."

Gonzales could not satisfy critics who said he had lost credibility over the Justice Department's handling of warrantless wiretaps related to the threat of terrorism and the firings of several US attorneys.

As attorney general and earlier as White House counsel, Gonzales pushed for expanded presidential powers, including the eavesdropping authority. He drafted controversial rules for military war tribunals and sought to limit the legal rights of detainees at Guantanamo Bay -- prompting lawsuits by civil libertarians who said the government was violating the Constitution in its pursuit of terrorists.

There were indications that the development came suddenly. Bush normally handles Cabinet resignations with efficiency, only allowing news of them to leak when a successor has been chosen and appearing with both the person departing and the replacement when the public announcement was made. That was not to be the case this time, the official said.

"Alberto Gonzales was never the right man for this job. He lacked independence, he lacked judgment, and he lacked the spine to say no to Karl Rove," said Senate Majority Leader Harry Reid, D-Nev.

"This resignation is not the end of the story. Congress must get to the bottom of this mess and follow the facts where they lead, into the White House," Reid warned.

The flap over the fired prosecutors proved to be the final straw for Gonzales, whose truthfulness in testimony to Congress was drawn into question.

Lawmakers said the dismissals of the federal prosecutors appeared to be politically motivated, and some of the fired US attorneys said they felt pressured to investigate Democrats before elections. Gonzales maintained that the dismissals were based the prosecutors' lackluster performance records.

Thousands of documents released by the Justice Department show a White House plot, hatched shortly after the 2004 elections, to replace US attorneys. At one point, senior White House officials, including Rove, suggested replacing all 93 prosecutors. In December 2006, eight were ordered to resign.

In several House and Senate hearings into the firings, Gonzales and other Justice Department officials failed to fully explain the ousters without contradicting each other.

During his congressional testimony, Gonzales answered "I don't know" and "I can't recall" scores of times and even some Republicans said his testimony was evasive. Bush, however, praised Gonzales' performance and said the attorney general was "honest" and "honorable."

US attorneys serve at the pleasure of the president, and can be removed. But congressional Democrats said politics played an unusually critical role in the ouster of several prosecutors.

In 2004, Gonzales pressed to reauthorize a secret domestic spying program over the Justice Department's protests. Gonzales was White House counsel at the time and during a dramatic hospital confrontation he and then-White House chief of staff Andrew Card sought approval from then-Attorney General John Ashcroft, who was in intensive care. Ashcroft refused.

The White House subsequently reauthorized the program without the department's approval. Later, Bush ordered changes to the program to help the department defend its legality. The domestic surveillance program was later declared unconstitutional by a federal judge and since has been changed to require court approval before surveillance can be conducted.

Similarly, Gonzales found himself on the defensive in early March for FBI's improper and, in some cases, illegal prying into Americans' personal information during terror and spy probes. On March 9, the Justice Department's inspector general released an audit showing that FBI agents, over a three-year period, demanded telephone and Internet companies to hand over their customers' personal information without official authorization.

The damning audit also found that the FBI had improperly obtained telephone records in non-emergency circumstances, and concluded that it underreported to Congress how often it used national security letters to ask businesses to turn over customer data. The letters are administrative subpoenas that do not require a judge's approval.

Gonzales declared himself upset and frustrated over the findings. But lawmakers said they had begun to lose confidence in him.