The secretary of state often is described as the president's principal foreign policy adviser, but the definition does not always match reality. Certainly not in the case of Colin Powell (search).

Down to his final days in office, Powell has been by his own admission ideologically out of step with many of his senior-level colleagues in the Bush administration.

"I'm a little bit out of the mold you would expect," Powell told an interviewer last year. He acknowledged that he was more liberal than others on President Bush's foreign affairs team.

Just this week, Powell's deputy secretary, Richard Armitage (search), outlined a strategy that he and Powell have used, going public with dissenting views to influence administration policy.

"You don't want a government that sees everything the same way," Armitage told National Public Radio's "Morning Edition." "That would be bad - it would lead to bad government, in my view."

Powell has given himself a conservative rating of "60, 65" percent out of a possible 100 percent. Vice President Dick Cheney was in the 90 percent range, Defense Secretary Donald H. Rumsfeld and national security adviser Condoleezza Rice (search) - Powell's designated successor - were "between 80 and 90 percent," the secretary said.

When it came to competing for influence with Bush, Powell lagged behind all three, according to James Mann, author of "Rise of the Vulcans," a history of Bush's foreign policy advisers.

Powell's experience is not without precedent.

William Rogers, Cyrus Vance, Warren Christopher and Madeleine Albright found in varying degrees that colleagues - usually the national security adviser - held more sway with the White House than did the secretary of state.

"It's a myth that the secretary of state is always the top foreign policy guy in an administration," Mann said.

Rice, whose confirmation hearings begin Tuesday, probably will have more clout with Bush because of her close working relationship with the president over the past four years.

Michael Franc of the Heritage Foundation, a conservative think tank, says Powell was forthright in making his views known in the administration's deliberations.

"Whenever the decision was contrary to his advice, he nevertheless remained a loyal soldier to Bush," Franc said.

Powell's chief rival often was Cheney, especially evident in August 2002. Powell's department was pushing hard to resume U.N. weapons inspections In Iraq. Cheney was denouncing them as a waste of time. Powell won that argument, but he lost many others.

Cheney interceded on North Korea (search) policy, insisting in December 2003 on a tougher line toward the communist-ruled country than the State Department wanted.

At the time, the administration was preparing for six-nation talks, with the goal of breaking an impasse over North Korea's nuclear weapons program.

Franc says Cheney has been "much more potent" on foreign policy issues than any other vice president. As a former defense secretary and former member of the House Intelligence Committee, Cheney brought considerable foreign policy experience to the job.

In a highly unusual move, Cheney appointed to his staff experts on Europe, the Middle East, China and other areas. The result, Mann said, was an "alternative NSC" to Rice's National Security Council (search). Cheney, as the No. 2 official in government, was able to pull rank on Powell and did.

As Mann sees it, conservatives were determined to prevent the more moderate Powell from accumulating too much power. "Conservatives were afraid of Powell," he said.

Powell never wavered in publicly defending Bush's Iraq policy, but the secretary may have hurt himself with the White House in other ways.

Powell presumably was the source of unflattering passages about Cheney and other administration figures in Bob Woodward's "Plan of Attack," a book about the run-up to the Iraq war. For instance, when Cheney tried to convince Powell that intelligence reports established a link between Iraq and Al Qaeda (search), Powell dismissed the vice president's evidence as "worse than ridiculous," Woodward wrote.

The phrase was Woodward's, but it gave Powell's rivals ammunition to portray the secretary as less than a good soldier and to lobby for limiting him to one term at the State Department.

Influence with the White House is but one measure of Powell's tenure. His prestige with the Congress helped reverse a long slide in appropriations for the foreign affairs budget.

He fought hard for democratic change around the world and for victims of humanitarian disasters, including those affected by last month's Indian Ocean tsunami (search) and the fighting in Sudan's Darfur (search) region.

But he will best be remembered for the speech to the U.N. Security Council (search) on Feb. 5, 2003, when he said Iraq's Saddam Hussein had doomsday weapons that violated U.N. sanctions.

This past week, the White House said it was calling off the search for the weapons because none had turned up after 18 months.