"I can't see how Temer survives this," said David Fleischer, a political science professor at the University of Brasilia. "There are just too many people against him now."
The country's main Ibovespa stock index dropped 10 percent within 90 minutes of opening and trading was stopped for 30 minutes. The Brazilian Real lost 8 percent of its value against the U.S. dollar in the first half of the day.
The scandal deepened at dawn Thursday as police searched the Rio de Janeiro home and Brasilia office of Sen. Aecio Neves, who nearly won the presidency in 2014 and planned to run again next year.
Neves is being investigated in several corruption cases related to the "Car Wash" probe into kickbacks to politicians. He has denied wrongdoing.
Late Wednesday, Globo reported that Neves had been recorded asking JBS meat-packing company executive Joesley Batista for $700,000 to pay for his "Car Wash" defense. On Thursday, the Supreme Federal Tribunal, the country's highest court, suspended Neves from office indefinitely.
Neves' whereabouts Thursday were not known. Attempts to reach him for comment were not successful.
Globo also reported that Batista had recorded Temer endorsing a bribe to silence former Speaker of the House Eduardo Cunha. In a statement late Wednesday, the president's office said Temer did not participate or authorize any attempt to keep Cunha from reaching a plea bargain with Justice (officials)."
If confirmed, the tape could prove devastating for Temer, whose administration has lurched from one crisis to another since he took office just over a year ago.
Cunha led the impeachment fight that removed Dilma Rousseff from the presidency last year and put Temer, then the vice president, into power. Cunha was later imprisoned on a 15-year sentence for corruption.
The statement from Temer's office confirmed that the president did meet with Batista in March. According to the Globo report, Batista secretly recorded the conversations with Temer and Neves and gave them to justice officials as part of plea bargain negotiations.
The report said that when Temer was told Cunha was being paid to keep silent, the president responded: "You have to keep that up, all right?"
Globo did not release the recordings or say how they were obtained.
JBS representatives did not respond to emails sent by The Associated Press seeking comment.
Temer and Cunha are members of the same party and were previously allies. However, they appear to have had a falling out amid a growing investigation into corruption involving the state oil giant Petrobras. Since launching three years ago, the "Car Wash" probe into billions of dollars in kickbacks has put several top businessmen and politicians in jail.
Many believe that Cunha, who was widely viewed as Brazil's most powerful politician before being ensnared in several corruption cases, could provide damaging testimony about dozens of others if he reaches a plea bargain with investigators.