Could congress sink giant anti-corruption drive?

As Brazils biggest ever corruption probe creeps higher up the political food chain, there are signs that Congress could be looking for a way to bring it to an end.

The probe codenamed operation Car Wash has already seen charges or convictions brought against some of Brazil's most powerful figures, ranging from ex-president Luiz Inacio Lula da Silva to the current Senate speaker and leading business executives.

They're accused of participating in a mammoth embezzlement scheme in which businesses bribed politicians or illegally paid into their party campaign funds in order to secure inflated contracts at state companies, especially oil flagship Petrobras.

The heat could soon grow even fiercer for Brazil's elite with an expected plea bargain between prosecutors and Odebrecht, the construction company at the heart of the pay-to-play scheme with Petrobras.

"Without doubt this is worrying and it explains attempts to limit the investigations. There are a lot of people with problems with Car Wash," said Onyx Lorenzoni, a deputy in the lower house with the DEM party.

Escape route?

"The closer the investigations get to those in power, the more reactions there'll be. If there's less impunity, those who imagine themselves as untouchable will try to create mechanisms to block the investigations," Roberto Veloso, president of the Association of Brazilian Federal Judges, told AFP.

Ironically, one of these measures could be a proposed law toughening anti-corruption rules.

The measure would stiffen penalties for undeclared donations to political campaigns. However the sting in the tail is that the law would not apply retroactively, effectively giving the parties already suspected of receiving dirty money an amnesty.

But the idea is popular in Congress where fear of operation Car Wash is rampant.

"If you criminalize all those using (slush funds) you're going to take out this entire political generation," an official with one of the main parties, who asked to remain anonymous, told AFP.

Battle with judges

The Senate president, Renan Calheiros, is one of the highest profile names in the Car Wash crosshairs.

A major scandal blew up in the capital Brasilia last month when federal police arrested four Senate police officers who'd allegedly been sweeping for listening devices planted by prosecutors.

Calheiros was furious and called for pension schemes to be cut for judges who are found guilty of violations during their service. The prosecutor general, Rodrigo Janot, shot back that this could lead to criminalizing judges for their work.

The Senate is also looking into public sector salaries, a move that is widely seen as aimed at hurting the tough judiciary.

"This is aimed at Car Wash," said Veloso, the head of the judges' association.

Meanwhile, the lower house has shelved for now a bill that sought to give amnesty to executives if their businesses admit guilt and aid investigators.

"If this bill is approved in the middle of the night... it will allow amnesty for crimes investigated by Car Wash," prosecutors said in a notably strong statement.