The tale of Brazil’s political crisis is one of betrayals, and the most explosive one may be yet to come.

Marcelo Odebrecht, the former head of Brazil’s largest construction conglomerate who was arrested in a massive corruption scandal, is trying to reduce a 19-year sentence through a plea bargain. Its potentially devastating impact on the political class was made clear in a chat between convalescent former president Jose Sarney, 86, and a longtime pal. “Odebrecht will show up with a 100-caliber machine gun,” Sarney said.