Incumbent President Dilma Rousseff of the Workers’ Party defeated Social Democratic Party challenger Aécio Neves in a runoff vote Sunday to gain re-election for a second 4-year term. With more than 99% of ballots counted, Ms. Rousseff had 51.5% of the vote versus 48.5% for Mr. Neves. The vote brought to an end three months of election campaigns marked by the death of one of the key candidates in the race, and sharp reversals in voting preferences shown in polls. Ms. Rousseff, a former combatant against Brazil’s military regime, rose to office as the protege of former Brazilian president Luiz Inácio Lula da Silva. Mr. Neves, a senator and former governor, took strong support in Brazil’s most populous and industrialized state of São Paulo, but lost to Ms. Rousseff in his home state of Minas Gerais, where a victory was deemed critical. Ms. Rousseff, meanwhile, took strong support in Rio de Janeiro and the large northeastern region of the country. With the victory, Ms. Rousseff will inaugurate the fourth consecutive term of the country’s Workers’s Party government. This year’s presidential campaign took a roller coaster path, with the death of presidential challenger Eduardo Campos in a plane accident in August. Mr. Campos. of the Socialist Party was substituted by his vice-presidential running mate, high-profile environmentalist candidate Marina Silva. Ms. Silva, however, came in third place in a first round election on Oct. 5, and subsequently endorsed Mr. Neves campaign. Mr. Neves began the second round campaign in a leading position in polls, but that was undermined throughout the month by a negative ad campaign run by Ms. Rousseff. Despite staging a late comeback to achieve victory, analysts said Ms. Rousseff was not left in a strong position to govern as the election was won by the closest margin since Brazil returned to a democratic regime in 1989. With her return to the job, Ms. Rousseff will now be faced with the task of bringing together a strongly divided electorate and congress, and returning the country to a path of growth. Brazil’s economy in the second quarter dipped into a recession amid slow economic activity, elevated interest rates, and inflation that has topped the 6.5% upper limit of the country’s annual inflation targeting band.