- First official results, exit polls show Tadic's party gaining 25% of vote
- That's one percentage point ahead of Nikolic's right-wing Progressive party
- Progressives, however, say their own polling show they have a narrow lead
- Nikolic, Progressives lean pro-EU
Serbian President Boris Tadic and his challenger Tomislav Nikolic were heading for a run-off with initial results showing Tadic and his Democratic party slightly ahead in presidential and parliamentary elections.
The elections are the first since the overthrow of strongman president Slobodan Milosevic in 2000 in which both leading presidential candidates and party blocs claim to support Serbia's integration into the European Union.
The country seemed set for a continuation of a moderate, pro-European coalition after both the first official results and exit polls showed Tadic's party gaining about 25% of the vote, about 1 percentage point ahead of Nikolic's right-wing Progressive party.
In the presidential poll, initial figures gave Tadic 26 per cent, also a point or so ahead of Nikolic. With neither candidate passing the 50 per cent barrier -- in a field of 12 candidates -- the two will go into a second round on May 20.
Nikolic's Progressives challenged the initial projections, however, claiming their own polling showed they had a narrow lead.
Some analysts question the depth of the pro-European conversion of Nikolic, former right-hand man to Vojislav Seselj, now on trial for alleged war crimes in The Hague, in the nationalist Radical Party. Tadic's rival Democratic party has also run a campaign highlighting the gap between Nikolic's rhetoric now and what he was saying a few years ago.
Even in the last elections in 2008, Nikolic ran against Tadic on a nationalist pro-Russian and anti-EU platform. But he and his followers later broke with the Radicals and formed the avowedly pro-EU Progressive party, taking many former Radical voters with them.
The initial results were a reversal of pre-election opinion polls that had shown both Nikolic and the Progressives slightly ahead of Tadic and his Democratic party, with voters penalizing the latter because of Serbia's poor economic performance.
The focus in the campaign has been on the economy, with unemployment running at 24%, and lackluster growth last year of 1.6% expected to slow to about 0.5% this year.
Serbs have also faced austerity measures to get public finances under control and could see more tight controls on spending if Serbia is to get a suspended IMF credit line back on track.
But the focus on economic issues has been in contrast to previous elections that posed a starker choice between moving towards the EU or more nationalist and pro-Russian policies.
Even if he finished second in the first round, pollsters had forecast Tadic might scrape to victory ahead of Nikolic in the second.
The kingmaker could be Ivica Dacic, leader of the Socialists -- Milosevic's former party -- who might demand the job of prime minister as the price of supporting either candidate. Initial results put Dacic third in the presidential poll, on 14.6%.
International peacekeepers in Kosovo, the former Serbian province that declared independence in 2008, were on high alert for possible clashes with the majority Albanian population as authorities allowed the Serbian minority there to vote in the elections. But the polls were reported to have passed without incident.