Nationalist opposition candidate Tomislav Nikolic is claiming victory in Serbia's runoff presidential election.

An unofficial estimate gives Mr. Nikolic 49 percent of Sunday's vote, ahead of incumbent President Boris Tadic, who had 47 percent.

The independent Center for Democracy and Free elections says the outcome will likely stay that way. Turnout was less than 50 percent; some voters said they do not like either candidate.

Both candidates supported Serbia's bid for membership of the European Union. But with a sour economy and 24 percent unemployment, Mr. Nikolic argued it is time for a change in the country's leadership.

Mr. Tadic was seeking a third term. He finished ahead of Mr. Nikolic by a small margin in the election's first round, earlier this month.

Mr. Nikolic's populist Serbian Progressive Party accused Tadic's Democrats of widespread vote fraud, but those complaints were rejected by Serbian election officials and foreign monitors.

A former member of the ultranationalist Radical Party, Mr. Nikolic once allied himself with the late President Slobodan Milosevic, who died in 2006 while on trial for war crimes.