Serbian pro-Western President Boris Tadic said Wednesday, April 4, that he is resigning, paving the way for an early presidential election where he will face a strong challenge from a nationalist candidate, The Associated Press reported.

Serbia's parliament speaker is expected to call the vote for May 6, the same day when parliamentary and local elections are already scheduled.

In the presidential vote, Tadic will be challenged by nationalist candidate Tomislav Nikolic who has received tacit support from Russia.

Tadic, who has worked hard to bring Serbia closer to the European Union, said the challenge will be tough, and called on voters to choose which way they want the country to go.

"I'm offering a road of European integration," Tadic said. "I will run in that election with optimism because of the positive trends in our country."

Tadic's presidential term would have expired at the end of this 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.