By Americo Martins
Head, BBC Brazilian Service
The Brazilian political establishment has been shaken by mounting claims of corruption within the ruling Workers Party (PT).
So far, however, it appears not to have affected the popularity of President Luiz Inacio Lula da Silva.
PT has a minority in Congress and it has been accused of having paid monthly bribes to congressmen from other parties to secure much-needed votes for the government's legislative projects.
Despite the difficulties, President Lula remains popular
It has also been accused of distributing top jobs in government and state companies to nominees of allied parties.
The accusations have not been proven so far and the party denies all the allegations. But four of PT's top leaders have resigned from their posts.
This is not the first time allegations of corruption have been levelled at Brazilian politicians.
Several previous governments are known to have offered favours and posts in state-run companies and ministries to political leaders in exchange for support in Congress.
This has been seen by many commentators as a normal requirement of the country's political system, which is based on several catch-all parties that would lend their support to any government in Congress in return for key posts in the public sector.
What makes this scandal different is that PT has always claimed to be an ethical party.
PT came to power in 2002 vowing to clean up politics. It also promised to promote deep social changes to narrow the huge gap between the many poor and the very few rich.
During its years in opposition, the party heavily criticised various administrations for their lack of transparency and supported several corruption investigations.
Now PT is being seen by more and more people as just another political party that would adopt any strategy to remain in power for as long as possible.
"Even with the possibility of recovery in the future, the party has lost its halo of probity," says political scientist Ricardo Guedes, director of Instituto Sensus, which carries out political and opinion surveys.
Leaving the party
The corruption allegations were a disappointment to millions of Brazilians who voted for Mr Lula in 2002 and backed claims that the party had a "historic opportunity to change the country" and that it did not have "the right to make mistakes".
Now some supporters are deserting the party.
There is also talk of left-wing MPs considering leaving the party. They have long complained about what they perceive to be President Lula's "neo-liberal" economic and social policies, and see an opportunity to walk away.
The party came to power in 2002 vowing to clean-up politics
"The government has lost its political drive, without a doubt," says Fabio Wanderley Reis a political scientist and professor at Universidade Federal de Minas Gerais (UFMG). "What the government can do now are basically defensive manoeuvres to keep some control over the political scene."
One of these "manoeuvres" was a recent cabinet reshuffle that President Lula was forced to make to accommodate more ministers from allied parties, a move that may bring him some support in Congress but could also alienate parts of PT further.
Despite all the difficulties, however, Mr Lula remains popular.
A recent opinion poll by Instituto Sensus suggested that almost 60% of Brazilians approve of the president's personal performance.
The same survey suggested that he would also be easily re-elected if elections were held now. The next election is scheduled for next October.
Ricardo Guedes identifies two main reasons for this phenomenon: The good performance of the Brazilian economy and a political operation to detach the president from the scandal.
"In the economic aspects, there are three main reasons for Mr Lula to remain popular. First, there has been a reduction in the unemployment levels with the creation of three million jobs during Mr Lula's term in office. Second, he has instigated social programmes that give direct assistance to 7.5 million families, and third, the minimum wage (which is still about US$120 a month) recently went up," he says.
Mr Guedes says that the political operation to protect the president has been orchestrated by the opposition. According, to him some political parties in opposition feared that a weakened president would open the door to a deeper institutional crisis.
The director of Instituto Sensus says that this was a tactical mistake by the opposition and that the risk of a very deep institutional crisis is still low.
Professor Wanderley Reis identifies yet another factor for Mr Lula's strong popularity.
"The popular electorate is not so interested in politics and it is badly informed," he says.
According to him, this may change with time as more people become aware of all the implications of the allegations.
Or if any proof of Mr Lula's direct involvement in the allegations, or omission to act against them, is found.