The International Atomic Energy Agency (IAEA) on Saturday said al-Baradai was alone in the race for the organisation's top job as no other candidates had come forward before the deadline for nominations at the turn of the year.
"No new candidates were submitted for the position of director general," IAEA spokeswoman Melissa Fleming said.
Al-Baradai, an Egyptian lawyer, has headed the IAEA since 1997.
Some US and other countries' officials have privately complained that he was soft on Iran and Iraq. They also accused him of withholding information from the IAEA board of governors - information that could have boosted the US campaign to refer Iran to the UN Security Council for economic sanctions.
"No new candidates were submitted for the position of director general"
Al-Baradai says there is no clear proof that Washington is right about Iran seeking the nuclear bomb. But he has repeatedly said the jury was still out.
Countries on the IAEA's 35-nation board of governors will attempt to reach a consensus before deciding whether to re-elect al-Baradai. Diplomats say that could take several months given Washington's opposition to him.
However, Washington's efforts to oust him were damaged last month by allegations that the United States had access to wiretaps on al-Baradai's telephone.
The administration of US President George Bush has a long history of dissatisfaction with al-Baradai, which began with his refusal to back US allegations that Saddam Hussein had revived his clandestine atom bomb programme.