Lawmakers gathered enough signatures to establish a joint investigation by both chambers of Congress that will look into cost overruns and allegations of corruption in the building or overhaul of 12 stadiums that will host the global football event.
The signatures still have to be verified and the petition confirmed by both chambers, which will not happen until August, allowing time for the government to convince lawmakers to withdraw their support and scuttle the probe.
In a sudden outburst of national discontent that shocked politicians, Brazilians took to the streets in June to express their anger at the high cost of living and poor quality of public transport, health and education services, as well as overspending on the stadiums for the World Cup, an event that is meant to crown Brazil's emergence as a world economic power.
The main target of public ire was Brazil's political class, which most Brazilians see as corrupt and self-serving.
Protests were fuelled by the hosting of the Confederations Cup, a warm-up for the World Cup. Demonstrators demanded improved public services rather than costly mega-events like the World Cup and the Olympic Games set for 2016 in Rio de Janeiro.
"In the wake of the protests, Congress must change its attitude and open this investigation demanded by the people," said Senator Alvaro Dias of the main opposition party PSDB, which initially requested the probe.
"No doubt there will be major revelations," Dias said.
The investigation will look at cost-overruns in building new stadiums such as the Mane Garrincha National Stadium in Brasilia, which is expected to cost more than 1.2 billion reais or double the original price tag.
Six of the 12 stadiums have been delivered for what some analysts say will be the most costly World Cup.
President Dilma Rousseff's government originally hoped to build the stadiums with private capital, but the arenas ended up depending on public funding. She has said the money will be repaid to the state.
- Politics & Government