a surprisingly strong showing in parliamentary elections, but faced the specter of a protracted power struggle after nationalist rivals vowed to join forces and form a government. The challenge cast a shadow over President Boris Tadic's claim of victory in Sunday's vote, and triggered fresh political turmoil in a country divided over whether it should join the EU or shift toward Russia and revert to its nationalist past.
Tadic proclaimed "a great day for Serbia" after projections by an independent monitoring group and partial results from the state electoral commission gave his Coalition for a European Serbia a 10 percent lead over the ultranationalist Radical Party.
"The citizens of Serbia have confirmed Serbia's European path," he said. "Serbia will be in the European Union. We have promised that, and we will fulfill that."
But Radical leader Tomislav Nikolic urged his allies to pull together.
Nikolic said he would meet Monday with Prime Minister Vojislav Kostunica's conservative coalition and former Serbian strongman Slobodan Milosevic's Socialists to form a government, "because ideologically we are very close."
Any alliance that can muster a simple 126-seat majority in the 250-seat parliament can govern. Although Tadic's coalition appeared assured of 103 seats, the Radicals were poised to get 76 seats. If they joined forces with Kostunica's bloc, with 30 seats, and the Socialists, with 21, the combined strength would be 127 seats.
Nikolic also accused Tadic of inciting violence by proclaiming victory. Tadic, in turn, made clear he saw Sunday's outcome as a mandate to take the country into the EU. He, too, was expected to court the Socialists in an attempt to support his government.
"I'm sure that those who wanted to return Serbia to the 1990s will try to overturn the electoral will of the people, but I will not allow it," Tadic told supporters, adding that he would propose a new prime minister from his own bloc.
"I'm getting ready for tough negotiations on the next government ... those talks will not be easy," Tadic said as thousands of his supporters waved party and EU flags, honked horns and blared the Rolling Stones' "Satisfaction" over loudspeakers in central Belgrade.
The European Union called the success of Tadic's coalition a "clear victory" by pro-European forces.
Tadic's opponents said their own vote tabulations confirmed the pro-Western forces' victory - an astonishing turnabout after weeks of speculation that the Radicals and Kostunica together would sweep to victory. The results instead left Kostunica fighting for his political future.
Kostunica said Sunday evening his differences with Tadic's coalition were "insurmountable," and that he was open to talks with the Radicals.