Bulgarian Prime Minister Boiko Borisov on Wednesday said his government would drop its support for UNESCO chief Irina Bokova and instead back EU Commissioner Kristalina Georgieva for the top UN post.

"We think it will be a more successful candidacy," Borisov said ahead of a government meeting.

The decision came two days after Bokova slipped into sixth place in the latest UN Security Council secret ballot. Earlier this month, Borisov had indicated that his government would continue to support Bokova's candidacy only if she finished in the top two in Monday's straw poll.

"Bokova has deployed a lot of efforts. We gave her a final chance for the latest vote... She fell even further and was overtaken by several other countries and other female candidates," Borisov said.

The nomination of Georgieva, the deputy president of the European Commission, will likely boost the chances of a Bulgarian taking over as head of the UN when South Korea's Ban Ki-moon steps down on December 31. But before Bokova can be replaced, she will need to file a letter announcing her withdrawal from the race - something she has said she has no intention of doing.

Bokova's candidacy was controversial, mainly because of her communist past, and rumors about her being dropped as Bulgaria's pick had been circling for some time.

Choosing the next UN chief

The process to elect the next UN headis a long and complex one. Former Portuguese prime minister Antonio Guterres, who also served as UN High Commissioner for Refugees (UNHCR) for a decade, is currently leading the race. In Monday's straw poll - the fifth informal vote by the 15-member Security Council - he was the only candidate to pick up the minimum nine votes required to become the nominee.

The next informal ballot is scheduled for October 5, but the five veto-wielding powers will be using colored ballots in that round to indicate whether they would block a candidacy.

"If there is a veto (against Guterres), the whole thing opens up," a council diplomat told AFP.

The job of the secretary-general has traditionally rotated among regions. Asia, Africa, Latin America and Europe have all held the post, and Eastern European countries including Russia say it's about time there was a UN chief from their region.

More than 50 countries are also campaigning for the UN to have its first woman secretary-general.

The nominee ultimately chosen by Security Council members will then be presented to the General Assembly for approval.

nm/kl (Reuters, AP, AFP)