To stand a chance of overturning Mr da Silva's huge lead, he must do two things, according to Gaudencio Torquato, a political scientist at Sao Paulo University.

ECONOMIST: Brazil's presidential election

Shorn of its own candidate, the governing coalition would split between the two, reckons Gaudencio Torquato, professor of politics at Sao Paulo University, making the final result unpredictable.

ECONOMIST: Brazil's election