Mohamed ElBaradei was virtually unknown when the United States engineered his candidacy eight years ago to run the United Nations' nuclear watchdog agency. He was a soft-spoken lawyer then, who left the Middle East of his youth for New York, first as a diplomat, then as an academic and finally as a career U.N. servant.

"What more could we ask for than a smart, respected Egyptian who cares passionately about the New York Knicks and nuclear nonproliferation?" said John Ritch, a former U.S. ambassador to the U.N.'s International Atomic Energy Agency who was instrumental in ElBaradei's selection.

Though he lacked any experience leading a major institution, U.S. support was enough for him to beat the only other contender -- a South Korean whose own country abstained -- in a 34 to 0 vote that launched ElBaradei's tenure as director general of the IAEA.

Yesterday, the agency's 35-member board unanimously awarded ElBaradei a third term running an agency whose findings and pronouncements could significantly bolster or undermine the Bush administration's push to confront Iran over its nuclear program.

Despite the warm beginning, ElBaradei's refusal in 2003 to confirm White House allegations that Iraq's Saddam Hussein had rebuilt his nuclear weapons program lost ElBaradei the U.S. support he had enjoyed for nearly six years.

In an interview with The Washington Post last fall, ElBaradei said the day the United States invaded Iraq "was the saddest in my life." It was not because he was a fan of Hussein, but because he was so sure Washington's assertions about weapons stockpiles and a secret program would be proved wrong.

Washington responded to ElBaradei's findings on Iraq's alleged weapons of mass destruction by trying to prevent him from taking a third term, despite requests from other board members that he stay on. "I am staying because I was asked, because so many board members made me feel guilty about leaving at such a crucial time," he said in an interview earlier this year.

The Bush administration launched a vigorous but solitary campaign -- including a complete halt of intelligence sharing, recruitment of potential replacements for ElBaradei and eavesdropping on him in search of ammunition against him. But as his popularity diminished in Washington, it soared elsewhere.

The IAEA coordinates nuclear safety around the world and monitors materials that could be diverted for weapons use. It has played pivotal investigative roles in four major crises in recent years: Iran, Iraq, North Korea and the nuclear black market run by one of Pakistan's top scientists.

ElBaradei became a champion in the eyes of many who opposed the war in Iraq, especially those in the Arab world. He is often asked for autographs, and occasionally applauded, when he lands in Arab capitals and is one of the most sought-after officials for media interviews.

"He is very popular; he's a celebrity," said Abderrahim Foukara, al-Jazeera's bureau chief at the United Nations. "Many see him as an Arab success story and a lot of Arabs take great pride that one of their own is this big shot who stood up to Washington, who meets all these heads of Arab states and is listened to and respected internationally."

At the same time, the IAEA's work doubled and delved into other controversial arenas such as Iran. There, too, its findings from a two-year investigation have not substantiated the Bush administration's certainty that the country is secretly working toward nuclear weapons.

John R. Bolton, Bush's nominee for U.N. ambassador who, as undersecretary of state for arms control, led the U.S. effort to oust ElBaradei, called those findings "impossible to believe." But they have not been overturned by competing evidence and, privately, Bush administration officials acknowledge that the IAEA's Iran investigation, now in its third year, has been thorough and that the agency has uncovered far more than U.S. intelligence could have learned without it.

The work and the war have changed ElBaradei, who will turn 63 this month. He still shuns the social circuit and prefers to spend most evenings at home with his wife in Vienna, but he has become far more vocal in recent years.

He has publicly called on the Bush administration to take part in negotiations between Iran and Europe, something the White House has said it will not do. He has called on the world's major powers to bring North Korea to the U.N. Security Council for possible sanctions, which both Washington and Beijing have resisted, and he wants tougher restrictions on exports of nuclear-related materials -- which corporate interests are fighting.

Robert Einhorn, who served as assistant secretary of state for nonproliferation during the Clinton administration, said the current White House "believes that ElBaradei's public appeals for the U.S. to engage with Iran go way beyond the IAEA's legitimate role as a technical agency."

"All U.S. administrations want the IAEA's director general to stay away from sensitive matters of policy -- except of course when the director general supports their policy," he said.

Last week, ahead of yesterday's vote, ElBaradei paid a visit to Washington and in a meeting with Secretary of State Condoleezza Rice, it was clear the U.S. campaign against him had come to an end. No one was willing to challenge him for the IAEA job, and no country was prepared to vote against him.

"We looked to the future and . . . did not discuss the past," he told reporters in Vienna yesterday when asked about the meeting.

In a sign of possible reconciliation, ElBaradei said that he was "humbled by the unanimous support," adding: "I am grateful to the United States."

Despite opposition from the United States, IAEA Director General Mohamed ElBaradei was approved for a third term.