The head of Brazil's Senate is facing mounting pressure to step down over an ethics scandal, threatening to weaken President Luiz Inacio Lula da Silva's control over Congress and derail his legislative agenda.
The resignation of Senate President Jose Sarney may throw Lula's congressional coalition into disarray, which would slow a campaign to rewrite the country's oil laws and revitalize a stalled corruption probe against state oil company Petrobras.
But the popular Lula could weather the storm if Sarney's centrist PMDB party stays in the ruling coalition and backs his anointed successor in next year's presidential race.
"My feeling is that he's not going to last much longer because it's reached a point in which he no longer enjoys the backing of the Senate," said Cristovao Buarque, a senator from the leftist PDT party and a government ally.
Roseana Sarney, the Senate chief's daughter and governor of the northeastern state of Maranhao, told Lula that her father would resign this week, according to a government official and two PMDB members privy to the conversation.
Congress was to reconvene on Monday after a two-week recess. But one group of senators has said it will effectively halt legislative progress by refusing to vote on any measures until Sarney is gone, Brazilian newspaper O Estado de S Paulo reported on Monday.
A former president of Brazil and a lifelong politician, Sarney faces a half dozen corruption charges that include embezzlement of state funds destined for cultural projects and arranging government jobs for relatives and family friends.
For months, Lula has defended Sarney to avoid jeopardizing his coalition, in which the PMDB is a key player, but appeared to distance himself from Sarney last week.
Lula is now scrambling to ensure that his replacement is a government ally. One name gaining traction is communications minister Helio Costa, a prominent PMDB member, an official close to Lula said on condition of anonymity.
Criticism of Sarney has swirled in editorial pages and television commentary for months but gained strength in late July after the leak of phone conversations of Sarney arranging employment for a granddaughter's boyfriend.
The mounting pressure comes as Lula is struggling to advance legislation on how energy companies can tap into massive crude reserves off Brazil's coast that could turn the South American nation into a major oil exporter.
The Senate fallout could also strengthen an opposition-led investigation that accuses Petrobras of accounting "tricks" to lower tax payments. The company denies the charges.