Pro-EU Serb leader fails to get clear victory

Less than half the population turned out to vote.

Analysts say high unemployment and other economic problems have led to a growing anti-EU sentiment in the country, which was granted EU candidacy status in March. The country has 24 percent unemployment and monthly salaries averaging at around €400.

Tadic, who has ruled the country for the past eight years, is aiming to push Serbia further towards full EU membership. He was instrumental in the arrest of war crimes suspects Ratko Mladic and Radovan Karadzic. He has also made pro-EU concessions on Kosovo.

"I expect even more support from citizens [in the run-off] ... because it is in their utmost interest: to lead them into the EU, to bring more investments, more regional cooperation," Tadic said.

Nikolic, is a former ultranationalist ally of war-time leader Slobodan Milosevic.

He once said he would rather see Serbia become a province of Russia than a member of the European Union. He now supports EU membership, but some commentators believe the change in position is a superficial ploy to gain votes.

He also campaigned against corruption and political cronyism and has vowed to improve living conditions.

A parallel parliamentary election indicates Nikolic's Serbian Progressive Party will become the largest in the parliament. It took 23.53 percent in the parliamentary vote, compared with 22.09 percent for Tadic's Democratic Party.

"The party, in [just] three-and-a-half years of existence, has won most of the votes in Serbia," Nikolic said.