The United Nations' nuclear watchdog has failed to elect a new director-general after five rounds of voting, opening the race to new candidates.
Neither Yukiya Amano of Japan or Abdul Samad Minty of South Africa were able to secure the two-thirds majority needed to replace Mohamed ElBaradei, the International Atomic Energy Agency's (IAEA) chief.
Amano was the leading candidate but fell one vote short of the number required on the second day of the two-day election in Vienna, Austria, which was attended by the IAEA's 35-nation board of governors.
Taous Feroukhi, chairwoman of the nuclear agency, said on Friday that the "slate of candidates is considered to have been wiped clean".
"Neither candidate was able to enjoy the two-thirds majority," she said.
Feroukhi said that member states would have 28 days to nominate new candidates, and that Amano and Minty would be able to run for the post again.
ElBaradei, 66, will retire from office in November after three terms stretching over 12 years.
IAEA officials plan to secure his successor by June, to ensure a smooth transition.
Proliferation challenges
The new director-general will have to face a number of challenges including controversy over Iran's nuclear programme and allegations that Syria has nuclear ambitions.
The change of guard comes at a time when the agency is seeking a significant increase in funding from member states over the next two years in order to carry out its duties effectively.
Steve Clemons, from the New America Foundation, told Al Jazeera that there was tension between those who fear Amano being a US puppet and desires from developing nations potentially with nuclear ambitions, who are seeing a pattern of nations being denied such technology.
"There's a real standoff between those like as Amano from Japan who want to be a classic preventer of non-proliferation. And those ... [like] Samad Minty ... who want to work with the developing world to provide legal mechanisms for the exchange of nuclear technology and for peaceful uses," Clemons said.
"And there's a real divide today because of the confusion about our nuclear non-proliferation treaty and where that's going to go."
Clemons said that other candidates may now enter the running for the position, and that there was a need for a director who could bridge the divide between an innovative outlook towards nuclear technology and its exchange and also prevention of proliferation.