Serbia's presidential run-off kicked off Sunday, which is seen by analysts as a referendum on the Balkan country's future.

Starting from 7:00 A.M. local time (0600 GMT) until 8:00 P.M. (1900 GMT), some 6.72 million eligible voters began casting their ballots to choose between pro-Western incumbent President Boris Tadic and his pro-Russian rival Tomislav Nikolic.

This is the first election to be held under Serbia's new constitution that went into effect after Montenegro declared independence from a union with Serbia in 2006.

The vote is a repetition of the scene in 2004 when Tadic of the pro-Western Democratic Party and Nikolic of the ultranationalist Serbian Radical Party competed in a presidential run-off.

However, the election this time will be a more fierce contest and is predicted to be one of the tightest ever in Serbia as the Balkan country is to face the imminent breakaway of its southern province of Kosovo.

Although latest polls gave Tadic a slight lead, pollsters admitted the race was too close to call.

The winner of the election could determine whether Serbia will continue on its path of pro-Western reform and closer ties with the European Union, or downgrade its ties with the pro-Kosovo West and brace for a kind of alliance with its traditional ally Russia.

The outcome will also decide how Serbia will react to the expected declaration of independence by Kosovo, which has been run by the UN mission and is dominated by pro-independence ethnic Albanians.

Both Tadic and Nikolic oppose independence for Kosovo, but Tadic has ruled out the use of force and would likely seek to preserve close ties with the European Union and the United States even if they recognize Kosovo's independence.

Nikolic has said Serbia must abandon its bid to become an EU member if the bloc upholds Kosovo's independence. He has called for closer ties with Russia, which supports Serbia in the Kosovo problem.

"I have just one small request for the EU: do not touch Kosovo and Metohija. Because we are a proud nation and we do not need the carrot and stick," Nikolic said during the campaign. "There is no EU for us if they take away our Kosovo."

Nikolic served as a deputy prime minister of the now-defunct Yugoslavia during the 1998-99 war in Kosovo, when NATO bombed Serbia for 78 days to stop its crackdown against the province's separatists.

Kosovo's Albanian leaders said they would declare independence days after the Serbian run-off, no matter who wins, and they expect the United States and most EU countries to follow up with quick recognition.

(Xinhua News Agency February 3, 2008)