Photo credit to Ricardo Moraes/Reuters.

It’s a stunning resurrection for a politician who spent most of the past two months languishing in third place.

But Aécio Neves, a Brazilian senator and the center-right candidate of the Partido da Social Democracia Brasileira (PSDB, Brazilian Social Democracy Party), will face incumbent president Dilma Rousseff, the candidate of the center-left governing Partido dos Trabalhadores (PT, Workers Party), in an October 26 runoff.

Rousseff led with around 41.5% of the vote to just 33.5% for Neves and 21% for Marina Silva, the one-time frontrunner and the candidate of the Partido Socialista Brasileiro (PSB, Brazilian Socialist Party). Silva became the party’s presidential candidate only in late August after her original running mate, former Pernambuco governor Eduardo Campos, died in an airplane crash on August 13.

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In the days and weeks after Campos’s death, Silva, a former environmental minister and a one-time Rousseff ally, vaunted to the top of the polls, which showed for weeks that she would easily advance to the runoff against Rousseff, and that she had a shot at defeating Rousseff in a one-on-one contest.

Instead, Rousseff will face Neves, the former governor of Minas Gerais, who suddenly seems to have the best chance of unseating the PT in the 12 years since it first came to power under the still popular former president Luiz Inácio Lula da Silva.

Polls showed that Silva was increasingly losing support in the final two weeks of the campaign, but few people would have predicted a Rousseff-Neves runoff even a week ago. Not only is it astounding that Neves edged out Silva, he won just 6% of the vote less than Rousseff, putting him in a strong position for the October 26 runoff.

In the next three weeks, Brazil will face its most contested presidential election in over a decade. Running as Lula da Silva’s popular protégé, Rousseff easily won the October 2010 presidential election against the PSDB’s José Serra, a former governor of São Paulo state and former São Paulo mayor, who trailed Rousseff in the first round of the 2010 race by 14% before falling short in the runoff.

Lula da Silva won the October 2006 election against the PSDB’s Geraldo Alckmin, who was set to easily win reelection as the current governor of São Paulo state, by far Brazil’s most populous, in Sunday’s general election.

Both Rousseff and Neves will attempt to win the endorsement of Silva and the support of her voters over the next three weeks. Silva, who began her career on the left, and who is a former member of the PT, might most naturally ally with Rousseff. Until earlier this year, the Brazilian Socialists supported the Rousseff government and the Lula da Silva government before it. Silva, as the candidate of Brazil’s Green Party, won 19.3% of the vote in the first round of the 2010 election.

As an outsider and a voice of political change, Silva could deliver wider appeal to Neves, who comes from a longtime political family and who lacks the kind of common touch that comes more easily to both Silva and Rousseff. On the campaign trail, Silva embraced relatively centrist economic plans, and the PSDB and Brazil’s investor community was already planning to back Silva against Rousseff in a potential runoff.

In some ways, Rousseff is getting the runoff she prefers, because she will not face a Silva candidacy that was trying to run both to the left and to the right of Rousseff — to the left in tone and symbolism (Silva, who grew up illiterate on an Amazonian rubber plantation, would have been Brazil’s first president of African descent), and to the right on substantive policy (in terms of budget cuts, tax policy and intervention to boost the value of Brazil’s currency, as well as Silva’s conservative views on social issues like gay marriage and abortion).

Instead, Rousseff can more credibly argue that Neves will roll back the generous social welfare programs that Lula da Silva introduced in the 2000s, including improvements that have ameliorated Brazil’s notorious economic inequality. Above all, the Bolsa Familia program that provides cash handouts to Brazil’s poorest families, along with substantive funding for health care and education, have becomes models for the rest of Latin America. The last PSDB-led government of Fernando Henrique Cardoso stabilized Brazil’s macroeconomic policies and reduced the country’s inflation, at the cost of incredibly unpopular economic upheaval that’s dogged the Brazilian center-right ever since.

But that doesn’t mean Neves is doomed to lose.

He might capitalize on widespread ambivalence about handing a fourth consecutive term to the Workers Party.  Protesters last summer, which started over the cost of rising public transportation, weakened Rousseff’s government. Rousseff’s party has been tarnished by scandal after scandal, including the Mensalão vote-buying scandal that dates to Lula da Silva’s first term, and  more recent allegations over kickbacks to politicians from the state-owned oil company Petrobras. Voters have also been unsatisfied by the nature of the Brazilian efforts to ‘pacify’ the favelas of Rio de Janeiro and São Paulo in advance of this year’s World Cup match and the 2016 Summer Olympics.

Moreover, Neves can point to a credible record in transforming the finances of Minas Gerais in his two terms as the state’s governor. With over 19.5 million people, Minas Gerais is the second-most populous state and historically, economically and cultural, one of the most important states in Brazil.

Both Lula da Silva and Rousseff have won the state by double-digit margins in past elections. Though the PDSB is set to lose the governorship of Minas Gerais to the PT in the simultaneous elections this year, Neves remains incredibly popular in the state, and if he can win its voters on October 26, he’ll stand a very good shot of winning the Brazilian presidency.