President Bush's cyber-security adviser is expected to resign from his post soon, sources said Tuesday.

Confusion still reigns over whether Richard Clarke, the quick-tongued White House adviser who moved from the FBI to the White House after the Sept. 11 terrorists attacks, has already submitted his resignation letter to the president.

One source said that he has, but a spokeswoman for Homeland Security Secretary Tom Ridge and National Security Adviser Condoleezza Rice said that the White House staffers at the President's Critical Infrastructure Protection Board haven't heard about his planned departure.

The president's counterterrorism coordinator at the time of the Sept. 11 attacks, Clarke is disinclined to accept a senior position in the new Homeland Security Department and plans to retire after three decades with the government, sources said.

He has not yet solicited an outside job, they said.

The sources, both inside and outside of government, said Clarke personally described his plans to them. Clarke has not said publicly what his plans are.

Clarke, probably most known for coining the phrase, "digital Pearl Harbor," in reference to the electronic threats faced by the United States that could seriously damage the nation's critical infrastructure, has served the White House longer than most staffers in history, being hired in 1992 from the State Department to counter threats from terrorism and narcotics.

In the position as cyber-security guru, Clark chaired a government-wide board that coordinates security, infrastructure protection and counter-terrorism against hits on government computer networks.

He was the top counterterrorism adviser even before the Sept. 11 attacks and did not get much of the blame for failing to anticipate them, but he did move out of his role to cyber-security not long after that.

In both the Clinton and Bush administrations, he "was the voice pushing this forward, calling out about the dangers," said William Wechsler, a former director for transnational threats on the National Security Council. "There's an easy reason why no one is pointing the finger at him."

Clarke, who has worked in the last four administrations in various security and intelligence positions, "was the single most effective person I worked with in the federal government," said Jonathan M. Winer, a former deputy assistant secretary of state. "When he was given the authority, he would stay with something every day until it got done. He's efficient and tough-minded. I never saw anyone else as good."

Clarke was "a bulldog of a bureaucrat," former national security adviser Anthony Lake wrote in a book two years ago. He said Clarke has "a bluntness toward those at his level that has not earned him universal affection."

"He's not an easy guy. He's very demanding. More than once people would come to me and complain, but that's why I wanted Dick in that job. He was pushing the bureaucracy," said Sandy Berger, Clinton's former national security adviser and Clarke's former boss.

But Clarke outlasted his critics, many say, because he had the ear of the president, could foresee the next crisis — for instance he warned of bioterror problems during the Clinton administration — and would quickly get the job done.

However, his impatience for bureaucratic procedures got him in trouble with Clinton's Joint Chiefs of Staff, which resented his bypassing military commanders and contacting Special Forces directly. He also launched covert operations out of the CIA — without adequate preparation or study, said Vincent Cannistraro, a former CIA counterterrorism chief.

"He gave the impression he was somewhat of a cowboy," Cannistraro said. "There was no love lost between Clarke and the CIA."

Clarke was with Rice and Vice President Dick Cheney in the situation room after the evacuation of the White House during the Sept. 11 attacks. His supporters said Clarke played a central role in the unprecedented decision to quickly ground the nation's airliners.

The Associated Press contributed to this report.