BELGRADE, Serbia, Jumada II 29, 1433, May 20, 2012, SPA - Voting has begun in Serbia's presidential runoff election that pits pro-European Union Boris Tadic against nationalists Tomislav Nikolic, the Associated Press reported. Sunday's balloting is key for Serbia's plans to become an EU member. Tadic was slightly ahead of Nikolic in the first round of voting on May 6, while Nikolic's Serbian Progressive Party won the most votes for parliament. --SPA 11:56 LOCAL TIME 08:56 GMT www.spa.gov.sa/1000063