Serbia’s ruling populists have declared victory at the polls in tense municipal elections in dozens of cities and towns, including a rerun vote in the capital Belgrade, as the opposition claimed major irregularities. The victory would cement the ruling right-wing party’s vast hold on power in the country that is a candidate nation for European Union membership. Prime minister and ruling Serbian Progressive Party chief Miloš Vučević told reporters that the party had swept the board, winning all but four municipalities. “From the north to the south, from Subotica to Nis, from Uzice to the east, …