What the Street is watching for is another shift in the dramatic story of Brazil's growth. Once thought to be on the path to massive economic wealth, Brazil's economy has slowed down while its inflation rate has sped up.

Protests before the World Cup showed that Brazilians were unhappy with their standard of living and President Dilma Rousseff's regime. It seemed like change was afoot — and prominent investors, like Mike Novogratz of Fortress Investment Group, have been betting that regime change will mean good things for the economy.

In Nomura's opinion, that change could still come if Marina Silva, Campos' running mate, decides to run in his place. Campos was third in the field, which included Rousseff (in first) and economist former Brazilian governor Aécio Neves.

Nomura analyst Tony Volpon is not, however, sure that Silva can be a lasting candidate if she remains in the race, as she trails her competitors in terms of resources.

What we can say is that Marina‟s entry into the race raises the chances of the election going to a second round, a negative for President Rousseff. Marina appeals to younger, urban voters, many of whom are undecided. Many analysts have pointed to the need to get these voters to the polls to get the election in a second round, and we believe this will now happen.

The Economist Intelligence Unit's Brazil analyst, Robert Wood, also thinks that Silva's introduction to the race would make a second round runoff more likely, which is bad for Rousseff.

However, if Silva decides not to run, her party will be without a candidate with her level of national star power. In that case, Rousseff could very well remain in office.