BELGRADE, Serbia - Voters in Serbia were choosing a president on Sunday in a closely contested race between pro-Western and nationalist candidates, held in the shadow of Kosovo's likely independence.

The vote is considered crucial as it could determine whether the troubled Balkan nation will move closer to the European Union or return to isolation similar to the era of late autocratic leader Slobodan Milosevic.

Looming over the vote is the expected declaration of independence next month by the separatist Kosovo province -- Serbia's ancient heartland now dominated by pro-independence ethnic Albanians.

Some 6.7 million people are eligible to vote in the election, including more than 100,000 in Kosovo, where the balloting was organized in Serb-held municipalities.

Nine candidates are vying for the presidency, but only two are considered serious contenders -- the pro-Western incumbent, President Boris Tadic, and his pro-Russian nationalist challenger, Tomislav Nikolic.

Telegenic and soft-spoken, Tadic advocates Western-style reforms and integration into the European Union, following over a decade of isolation and wars under Milosevic.

Tadic's campaign warned that Sunday's election was "decisive'' for Serbia's future, giving citizens a choice between a "road ahead and an errant road'' back into isolation.

"This is a vote for a better life,'' he said during the campaign.

Nikolic, on the other hand, has sought to evoke Serbs' nationalist pride and has played on the growing frustration over Western backing for Kosovo independence.

An ally of Milosevic, Nikolic ruled alongside the former president in the 1990s. His return to power likely would bury Serbia's pro-European aspirations and push the country back into isolation.

Pre-election polls have suggested that Nikolic will win more votes than Tadic in the first round of balloting, but not enough to pass the majority threshold needed to avoid a runoff on Feb. 3.

The support for Nikolic reflects the mounting nationalism in Serbia over Kosovo, but also the dissatisfaction of ordinary Serbs with the pace of pro-Western reforms launched after the fall of Milosevic in 2000.

Both Tadic and Nikolic reject independence for Kosovo, but Nikolic, unlike Tadic, has promised tough measures against the countries that recognize Kosovo's statehood.

Apart from the two front-runners, other candidates include young liberal leader Cedomir Jovanovic, who is the only politician in Serbia who accepts independence for Kosovo, as well as Popular coalition candidate Velimir Ilic and Socialist Milutin Mrkonjic, both counting on support from elderly, provincial voters.