Brazilian presidential challenger Aécio Neves Sunday made a last-minute turnaround to surpass Marina Silva for a spot in a runoff election against incumbent president Dilma Rousseff. With 100% of the vote counted, Mr. Neves, of the centrist Social Democratic Party, had 34% of the vote versus 42% for Ms. Rousseff, of the Workers” Party, and 21% for Ms. Silva, of the Socialist Party. Mr. Neves, a senator and former governor of Minas Gerais, made a strong surge in the final two days of his campaign, suggesting he was benefitted by a strong performance in the last of televised debates this week. The candidate made his best showing in the populous industrial state of São Paulo, surpassing Ms. Rousseff’s tally there, but trailed the president in his home state of Minas Gerais. The first round finish came as a surprise and an upset following a tumultous campaign in which support for popular environmentalist and former Senator Ms. Silva surged following her replacement of the Socialist Party’s initial candidate, Eduardo Campos, who was killed in a plane crash in August. In the wake of Sunday’s result Brazil will hold a runoff election on Oct. 26. In a concession speech late Sunday, Ms. Silva said the results of the vote signaled a desire for change among voters, but declined to define whom she would support for the runoff round.