A rule of geographic rotation suggests the next UN Secretary General should be from Eastern Europe. Several countries from the region have endorsed candidates.
Two women from Eastern Europe have already been nominated by their governments: Irina Bokova of Bulgaria, who currently serves as the director-general of the U.N. Educational, Scientific and Cultural Organization (Unesco), and Vesna Pusić, who serves as the first deputy prime minister and minister of foreign and European affairs of Croatia.
Two men - Danilo Türk, who served as Slovenia's president, and Srgjan Kerim, a Macedonian diplomat and former president of the U.N. General Assembly - have also already been officially nominated as candidates for secretary-general.
Intense debate over candidates will likely begin in the early summer in the hopes that the next head will be selected and overlap with Ki-moon before he steps down on Dec. 31, 2016.
Bulgaria's delay in submitting a candidate to take over as UN Secretary General prompted various politicians to criticise Bulgarian Government.
Former Foreign Minister Solomon Passy said that failing to nominate Bokova could dash Eastern Europe's chances for the office.
Former Bulgarian President Georgi Parvanov called on the government to immediately nominate Irina Bokova as a candidate for UN Secretary-General, threatening to withdraw his party's support if the cabinet fails to do so.
Parvanov is leader of left-wing Alternative for Bulgarian Revival (ABV), which is one of the two parties supporting the coalition government.
Political analysis by Plamen Asenov.
