Bush planned to act quickly, perhaps as early as Monday, to nominate Goss' successor. The leading candidate was Air Force Gen. Michael Hayden, the top deputy to National Intelligence Director John Negroponte, a senior administration official said.
Goss played an important role in the fight against terrorism and "helped transform the agency to meet the challenging times we're living in," White House spokeswoman Dana Perino told reporters Saturday as Bush flew to Oklahoma State University for a commencement address.
She said Goss "made significant steps in order to put all those transitional pieces in place and there was a collective agreement that now would be a time that we could have a new CIA director come in and take the ball and move the agency forward."
Goss, who met with Bush on Friday to tender his resignation, has offered little explanation for quitting after just 19 months. Goss was to deliver a commencement speech Saturday at Ohio's Tiffin University, one of a growing number of schools that offers programs in national security studies.
Negroponte, with the backing of the White House, recently raised with Goss the prospect that he should leave, and the two men talked about that possibility, a senior administration official said. The official spoke on condition of anonymity in order to give a fuller account of events.
"Reports that the president had lost confidence in Porter Goss are categorically untrue," Perino said.
An intelligence official, speaking only on condition of anonymity because of the sensitivity of his position, said Goss had stood up for the agency when there were differences with Negroponte's office, which was created about a year ago.
Goss was taking a stand against "micromanagement," the official said, and wanted the agency to "remain what its name says, the 'Central' Intelligence Agency."
Negroponte, Goss' classmate at Yale University, said in a statement that Goss worked tirelessly during a CIA transition period. "As my friend for almost 50 years, I will miss Porter's day-to-day counsel," he said.
Goss spent 40 years in federal and local government, including 16 years as a congressman and 10 years as a CIA operative in the 1960s and 1970s. While he was CIA chief, the agency struggled to forge a new identity in an era of government overhauls stemming from the Sept. 11 attacks and the flawed prewar intelligence on Iraq.
"CIA remains the gold standard," Goss said in a statement. "When I came to CIA in September of 2004, I wanted to accomplish some very specific things, and we have made great strides on all fronts."
Goss' departure was the White House's third major personnel move in just over a month, aimed at reinvigorating Bush's second term.
Republicans said Friday night that Hayden was thought to top Bush's short list of candidates to replace Goss. Among others mentioned: Bush's homeland security adviser, Frances Fragos Townsend; David Shedd, Negroponte's chief of staff; and Mary Margaret Graham, Negroponte's deputy for intelligence collection.
Hayden was National Security Agency director until becoming the nation's No. 2 intelligence official a year ago. Since December, he has aggressively defended the administration's warrantless surveillance program. He was one of its chief architects.
CIA officials dismissed suggestions that Goss' resignation was tied to controversy surrounding the CIA's executive director, Kyle "Dusty" Foggo. The FBI is investigating whether Foggo's longtime friend, defense contractor Brent Wilkes, provided prostitutes, limousines and hotel suites to a California congressman who pleaded guilty to taking bribes from Wilkes and others in exchange for government contracts.
CIA spokesman Paul Gimigliano said Goss' resignation also was not related to the recent firing of a CIA officer that Goss said had unauthorized contacts with the press; the firing that found support within the agency and the White House.
Bush nominated Goss in 2004, in the midst of a re-election campaign that was riddled with accusations about the botched prewar intelligence. Bush said he would rely on the advice of Goss on the sensitive issue of intelligence overhaul.
Goss, the former chairman of the House Intelligence Committee, came under fire almost immediately, in part because he brought with him several top aides from Congress who were considered highly political for the CIA. They developed particularly poor relations with segments of the agency's clandestine service.
By December, Congress passed the most sweeping intelligence overhaul in 50 years, relegating the CIA to a crowded second tier of 15 other agencies.
Hayden, the highest-ranking military intelligence officer, has been brought into management challenges before. In 1999, he was tapped to shake up the NSA as the Internet and new communications tools were frustrating the agency's eavesdroppers.
Were Hayden's nominated, Democrats would be sure to seize on his intimate connection to Bush's anti-terrorist surveillance program, which has drawn the ire of even some Republicans.
Bush aides have been looking for ways to rescue his presidency from sagging poll ratings and difficulties with the Iraq war and his agenda in Congress.
The shake-up began with the resignation of Andrew Card as chief of staff and his replacement by Joshua Bolten. Other changes have included the replacement of press secretary Scott McClellan with Fox News commentator Tony Snow.
It wasn't immediately clear what's next for Goss, 67. He was supposed to retire after representing a Republican district on Florida's West Coast for 16 years, but he became CIA director when Bush called in 2004.
Many former directors take consulting positions on corporate boards. Goss and his wife own a central Virginia farm, where they raise cattle, sheep and chickens.