Serbian President Boris Tadic is resigning, 10 months before the end of his mandate but intends to stand again in May.
It is thought this tactical move will boost his party’s chances in parliamentary elections, which take place at the same time.
Although his Democratic Party is trailing in the polls, the president’s personal popularity is strong.
Serbia’s outgoing government won welcome support after the country became an official candidate to join the EU. However it is still to prove its credentials. Progress towards EU accession could take a decade, depending on relations between Serbia and Kosovo.
Nationalist candidate Tomislav Nikolic of the Serbian Progressive Party is also expected to stand.