The field of candidates to head the UN atomic agency is down to a Japanese diplomat and a South African anti-apartheid activist. If neither achieves the required two-thirds majority, the race opens up to others.
IAEA's ElBaradei who had clashed with the US on Iran, steps down.
The two front runners for the leadership of the International Atomic Energy Agency (IAEA) in Vienna are Japanese diplomat Yukiva Amano, 62, and Abdul Minty, 69, a former anti-apartheid activist from South Africa.
The 35 members of the IAEA board failed to elect either candidate in three rounds of voting on Thursday and if neither man emerges with the two-thirds majority necessary to head the UN agency by Friday, the race will open up to a field of new candidates.
Both men are steeped in nuclear proliferation issues and have pushed for civilian uses of atomic energy. Japan's Amano is favored mainly by the rich industrial nations and has the lead at the moment, whereas developing countries tend to prefer Minty, according to unnamed diplomats cited by Reuters.
Nobel Peace prize winner ElBaradei steps down
The race is important since whoever the new IAEA head will be influences how the world meets the nuclear challenges posed by Iran, Syria or other volatile states allegedly seeking to develop the bomb.
Mohamed ElBaradei, the current director-general will step down in November after having served 12 years, but the board would like to have his successor in place by June to ensure a smooth transition.
The head of the IAEA is tasked with helping signatories to the Nuclear Non-Proliferation Treay pursue peaceful civilian uses of atomic energy, but during ElBaradei's tenure, the agency has assumed more of a watchdog role, monitoring nations that could be secretly developing nuclear weapons.
Vienna's IAEA has assumed a watchdog role for "rogue states".
ElBaradei, 67, a seasoned Egyptian diplomat and lawyer who shared the Nobel peace prize with the IAEA in 2005, has openly clashed with the Bush administration over what he viewed as Washington's hostile policy towards Iran and Iraq.
In spite of tensions with former President George W. Bush, whose justification for the 2003 Iraq war was the belief that Iraq was hiding weapons of mass destruction, ElBaradei secured a third four-year term at the IAEA with US backing.
"Nine too many" nuclear powers in the world today
Since succeeding Swedish diplomat Hans Blix in 1997, Mr ElBaradei's method of dealing with nuclear rows was to combine weapons inspections with engaging Iraq, Iran and North Korea.
"Verification and diplomacy, used together, can work," he has said. "The Iraq experience demonstrated that inspections can be effective even when the country being inspected is less than co-operative. All the evidence indicates that Iraq's nuclear weapons program had been effectively dismantled in the 1990s through IAEA inspection, (which) we were ready to conclude before the war."
Now that US President Barack Obama has said he wants to open a dialogue with Iran, ElBaradei's successor could benefit from Washington's commitment to new diplomatic efforts.
ElBaradei has always been a strong proponent of general nuclear disarmament. There are nine nuclear powers in the world today. "Clearly nine too many," he once said.