Serbia's pro-European alliance was to start coalition talks with smaller parties today to stave off a challenge from nationalist runners-up who say they too can form a government after yesterday's parliamentary election.
Monitors put the alliance led by the Democratic Party at 39 per cent of the vote, ahead of the Radicals on 29 per cent.
A rolling count by the state election commission put the Democrats at 36.7 per cent and the Radical Party at 28.5 per cent.
The election was fought on whether Serbs should swallow their anger over European Union support for the independence of Kosovo, the Serb province which seceded in February, or turn their backs on the bid for European Union membership.
The Democrats' leader, President Boris Tadic, told supporters: "Serbs have undoubtedly confirmed a clear European path. This is a great victory, but it's not over yet.
"I want us to be aware that we must form a new government as soon as possible."
The Radicals' leader, Tomislav Nikolic, said the Democrat claim of victory jumped the gun. There were "very clear possibilities of a coalition which does not include the Democratic Party", he said.
Mr Nikolic said he would talk to the two parties that share the Radicals' ideology, the Democratic Party of Serbia led by outgoing nationalist premier Vojislav Kostunica and the Socialists of the late Slobodan Milosevic.
Official results are due by Thursday night. Parliament must convene by mid-June and a government be formed by mid-September or the country must hold a new election.
The European Union welcomed the result and urged the quick formation of a government with a "clear European agenda".
The EU had made its preference clear before the vote, offering Belgrade a pre-membership pact and a visa facilitation deal that are implicitly conditioned on a Democrat win.
The main pro-EU parties campaigned as one and consolidated their votes in one bloc, slightly increasing their share of the vote over the last election in January 2007.
But they still made no great inroads into overall nationalist support, which remained at about 50 per cent of the 6.7 million electorate, spread among three parties.