BELGRADE, Serbia?- Serbian President Boris Tadic says he is resigning, paving the way for early presidential election.

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

In the presidential election, pro-Western Tadic will face a strong challenge from nationalist candidate Tomislav Nikolic.

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

Serbia's President Boris Tadic speaks during a news conference in Belgrade in this March 2, 2012 file photograph. Tadic said on April 4, 2012 that he was resigning 10 months before the end of his mandate, clearing the way for joint parliamentary and presidential elections in May when he will run for a new term.[Photo/Agencies]