SAO PAULO — Official vote returns indicate Brazil's leading presidential candidate Dilma Rousseff has been forced into a second-round runoff.Rousseff is the hand-chosen successor to popular President Luiz Inacio Lula da Silva.To win outright, a candidate needs to win 50 percent plus one vote.Brazil's Supreme Electoral Court reports Sunday that with 97.5 percent of the votes counted, Rousseff needs 3.4 percent for a first-round win, putting an outright win out of her reach.Rousseff will face her centrist Jose Serra in the Oct. 31 runoff.