With a dramatic announcement that the 2011 Egyptian revolution had been relaunched, Mohamed ElBaradei, a civilian opposition leader and a former United Nations official who won the 2005 Nobel Peace Prize for his work with the International Atomic Energy Agency, publicly aligned himself with the Egyptian Army on July 3, backing its overthrow of President Mohamed Morsi.

Then, in swiftly changing events, ElBaradei was designated interim prime minister of Egypt on July 6 by the recently appointed president, Adly Mahmud Mansour. Later on July 6, there appeared to have been hurdles confirming ElBaradei’s new position, and his possible advancement is now thrown into serious doubt. On July 7, the ultraconservative Egyptian party, Salafist Nour, countered ElBaradei’s appointment, saying he was too divisive for Egypt. Latest accounts said that ElBaradei could become vice president.

ElBaradei is decidedly on the other end of the political spectrum not only from Salafist Nour but also from the Muslim Brotherhood, Morsi’s affiliation — leading an alliance of liberal and left-wing parties, the National Salvation Front.

ElBaradei’s support of Morsi’s ouster was bold though perhaps not an unexpected step for him. He is a scholar of international law as well as a weapons expert who has been a strong voice in support of a more liberal, secular government in Egypt since the fall of Hosni Mubarak more than two years ago.

ElBaradei was initially considered a potential presidential candidate to challenge Morsi and the Muslim Brotherhood, but he withdrew from contention in the face of the power of Morsi’s following and the disunity of the opposition.

Leader of the Constitution Party, ElBaradei spent much of his life outside Egypt in diplomatic or UN service, and had at first been accused by many Egyptians of being out of touch with his own country when he returned to Cairo as protests against Mubarak’s military-backed regime began to grow, leading to its overthrow. Now, two and a half years later, ElBaradei was asking the army to step in and “protect the souls” of the Egyptian people.

ElBaradei, whose father was a prominent Egyptian lawyer and president of the Egyptian Bar Association, was born in Cairo in 1942. He received his first law degree from Cairo University and a doctorate in international law from New York University School of Law in 1974. His adviser at the university, the late Thomas M. Franck, a leading international law specialist, said in an interview with me in 2004 that there was only one word to describe ElBaradei: “Brilliant.”

Franck added that besides his scholarly achievements, his former student also developed into a skilled diplomat early in his career. After earning his doctorate, ElBaradei returned to the Egyptian foreign service, where he had worked before enrolling at New York University. Franck recommended that he be assigned to UN headquarters as a senior research fellow. By 1984, ElBaradei, by then a recognized specialist in arms control and the peaceful uses of nuclear technology, was named legal counsel to Hans Blix, the formidable director-general of the International Atomic Energy Agency, based in Vienna.

In 1993, ElBaradei became assistant director of international relations for the agency; in 1997, he succeeded Blix as the agency’s director-general for a four-year term. He was reappointed to a second term by the board in 2001, amid controversy and rumors that the American government was attempting to block his continued service.

ElBaradei’s relations with Washington were not always smooth. In particular, there were differences over how to handle Muammar el-Qaddafi, the former Libyan leader, who agreed to dismantle a developing nuclear weapons system late in 2003. UN officials said that the United States wanted to control the process and tried to undermine ElBaradei, as they had undermined and tried to discredit Blix in the months before the  2003 American invasion of Iraq. Blix had been head of the Iraqi disarmament program for the UN and wanted more time to carry out inspections in Iraq before the US acted.

ElBaradei has also been credited with taking an independent line on Iran, whereby working with Europeans, he could gain entrance to more nuclear facilities through diplomatic perseverance. ElBaradei had proved to be adept at dealing with “difficult people,” Franck said.

If ElBaradei emerges as a political leader or force behind the scenes in this yet-again tumultuous period in Egypt, his relations with the US will be watched closely by many in the Middle East and Europe. An internationalist fluent in English, ElBaradei is the cosmopolitan face of Egypt, but he could also bring to the table the same strong personality and sense of purpose that gave him the independence for which he was known a decade ago — and for which he shared the Nobel Prize for Peace in 2005 with the International Atomic Energy Agency.

The award was bestowed for ElBaradei’s efforts, the Nobel citation said, “to prevent nuclear energy from being used for military purposes and to ensure that nuclear energy for peaceful purposes is used in the safest possible way.” On that issue, President Barack Obama and ElBaradei are on the same page.

[This article was updated on July 6 and July 7.]

This story was first published in PassBlue. We have their permission to republish.