BRASILIA - Carnival revelers were still dancing in the streets of Brazilian cities on Wednesday but for President Michel Temer's government it was back to the reality of mounting corruption allegations that threaten its survival.

"Out with Temer" was a frequent chant against the unpopular president during the annual celebrations across a country hit by record unemployment and fed up with its political leaders.

On Wednesday afternoon the jailed former CEO of Brazil's biggest engineering group, Marcelo Odebrecht, was questioned by a judge investigating donations made to Temer's 2014 campaign, when he was the running mate for leftist leader Dilma Rousseff, who was impeached last year.

A source with access to Odebrecht's deposition said he confirmed an illegal payment to Rousseff's campaign manager Joao Santana, but added that he could not say if the then-president or her running mate knew about it.

Odebrecht said former finance minister Guido Mantega negotiated under-the-table donations for the 2014 campaign that totaled 300 million reais, but he denied they were bribes to obtain government contracts, the source said.

Odebrecht, who is seeking leniency to lower a 19-year sentence for corruption and money-laundering, said Temer did not directly request a donation at a dinner in 2014, though the matter was discussed in a general way.

The massive investigation into bribery and political kick backs, dubbed Operation Car Wash, threatens to bring down members of Temer's inner circle and has generated political uncertainty that is undermining business confidence and prolonging Brazil's two-year recession.

Electoral court judge Herman Benjamin is seeking to determine if a 10 million reais ($3.2 million) contribution allegedly sought by Temer was paid from graft money, as claimed by another Odebrecht executive in plea bargain testimony.

Temer has said the donation was legal and duly registered, but Benjamin could recommend annulling the Rousseff-Temer ticket, which would lead to the president's removal and election of a new leader by Congress if it is upheld by the full court.

The graft scandal endangers Temer's efforts to push unpopular austerity reforms through Congress aimed at curbing a growing budget deficit that cost Brazil its investment grade credit rating in 2015.

"The President's biggest challenge now is to prevent the CarWash investigation paralyzing his reform agenda in Congress," a Temer aide told Reuters, requesting anonymity because he was not authorized to speak about the government's worries.

The crisis will deepen in the next few weeks when Brazil's top prosecutor Rodrigo Janot will ask the Supreme Court to make public plea bargain statements of 77 Odebrecht executives who are expected to name up to one-third of Brazil's federal lawmakers for taking kickbacks.

Among the politicians at risk is Temer's chief of staff, Eliseu Padilha, who is on medical leave after prostate surgery but will have to face questions about a package of 1 million reais he allegedly requested as part an undeclared contribution from Odebrecht.

A lawyer and longtime friend of Temer's, José Yunes, has approached prosecutors to confirm the package was handed over at his office for Padilha but that he had no idea that it contained cash, leaving the chief of staff in a difficult position.

Reuters