BELGRADE, Serbia (AP) -- Pro-Western Serbian President Boris Tadic said Wednesday he is resigning, paving the way for an early presidential election when he will face a strong challenge from a nationalist candidate who has Russia's support.
Serbia's parliament speaker is expected on Thursday to scheduled the vote on May 6, the same day when parliamentary and local elections are to be held.
In the presidential vote, Tadic will be challenged by nationalist candidate Tomislav Nikolic who has received tacit support from the Kremlin. Several other candidates also are expected to run, but without real chances of winning.
Tadic, who has worked hard to bring Serbia closer to the European Union, said the challenge will be tough, and he urged voters to choose which way they want the country to go.
"I'm offering a road of European integration and preserving the country's integrity," Tadic said. "I will run in that election with optimism because of the positive trends in our country."
Tadic's presidential term was to end early next year. But he decided for an early vote apparently to boost the chances of his Democratic Party, which has been slipping in recent pre-election polls against Nikolic's populist Serbian Progressive Party.
"I think Tadic is the favorite to win the presidential vote and will bring a few percentage points more to the democrats," political analyst Ognjen Pribicevic said.
Nikolic expressed confidence he will defeat Tadic. If no candidate receives 50 percent of the votes in the first round, the top two contenders face a runoff.
"I hope the election campaign will be fair," said Nikolic, who was narrowly defeated by Tadic in two previous presidential elections.
Tadic's governing democrats are being blamed for the country's deep economic and social problems. The nationalists also claim Tadic is willing to sell off Serbia's cherished former province of Kosovo, which declared independence in 2008, at the expense of distant and uncertain membership in the European Union.
"I will never recognize Kosovo," Tadic said while announcing his resignation.
In recent years, Nikolic has won over disenchanted Serbs by railing against corruption and social injustice, and claiming to have shifted from being staunchly anti-Western to pro-EU.
Nikolic was deputy prime minister in a coalition government with late President Slobodan Milosevic in the late 1990s and backed his wars in the Balkans. Therefore, there is growing concern among Serbian liberals that his victory in the presidential election could plunge Serbia back into a confrontation with the West.
The self-proclaimed "Russia lover" seems to be the Kremlin's choice for Serbia's new leader, and he has made several recent trips to Moscow for consultations with top Russian officials.
Associated Press writer Jovana Gec contributed to this report.