In the face of pending corruption allegations likened to a ticking bomb, Brazilian President Michel Temer is building himself a bunker.

An embezzlement and bribery probe called Operation Car Wash has already shaken high level Brazilian politics for almost three years. But far from winding down, it's expected soon to escalate.

Prosecutors are looking into whether Temer and many others, often from his PMDB party, took part in a gigantic corruption network that embezzled from state oil company Petrobras and filled election campaign coffers with dirty money.

The president and some of his allies are among those implicated in testimony given in plea bargains by 77 executives from Odebrecht, a construction firm that ran a whole secret department just for bribing politicians.

The testimony remains secret. But it could soon be released by the Supreme Court -- and the president's team is scrambling to take cover.

"The approach of the tsunami has prompted the government to enact its emergency plan," said Bernardo Mello Franco, a columnist with Folha de Sao Paulo daily, reaching for yet another apocalyptic metaphor.

"The order has gone out to reinforce the dikes and try to protect friends with buoys and life jackets."

- Protecting the president -

According to leaked testimony, then vice-president Temer asked Odebrecht in 2014 to give the center-right PMDB millions of dollars in campaign funds.

He denies doing anything improper and a sitting president cannot be prosecuted for crimes that allegedly occurred before his term began.

But with large numbers of other politicians also expected to be implicated, the potential scandal could still be huge.

For sitting politicians accused of crimes, it will be up to the Supreme Court whether to authorize further investigations and whether to go to trial.

That's seen as an advantage compared to the fate of executives and ex-politicians caught in Operation Car Wash. They must instead face a set of crusading prosecutors and judges at a lower court level.

When the Supreme Court's main justice for Car Wash cases, Teori Zavascki, died in a plane crash in January, some worried the probe might be derailed.

Others questioned whether the crash, coming just as the Odebrecht time-bomb was being prepared, was even an accident.

But so far, the Supreme Court appears determined to press on and analysts say Temer's inner circle is scrambling to gain whatever advantage it can.

For example, earlier this week, Temer named a highly partisan figure to fill Zavascki's seat -- his justice minister, Alexandre de Moraes.

As Globo newspaper's columnist Miriam Leitao put it, "Temer was not being subtle."

"He wants to guarantee at least one vote (on the court) in his favor," Leitao added.

Temer also this week named one of his closest advisors, Wellington Moreira Franco, to a ministerial-level post.

The reshuffle was instantly criticized as an attempt to get Moreira Franco -- who like so many others has been implicated in the Car Wash probe -- out of the clutches of lower courts.

An intense legal battle erupted, with one judge barring the nomination, another overturning that decision and a third intervening again, leaving a final decision to the Supreme Court.

- Legislators feeling heat -

The government is not alone in getting edgy about the coming Odebrecht testimony. Congress and much of Temer's PMDB and allied PSDB party are anxious.

The speakers of the senate, Eunicio Oliveira, and of the lower house, Rodrigo Maia, have both been implicated in bribe taking in the Car Wash scheme. Their recent predecessors Renan Calheiros and Eduardo Cunha are also caught up in the affair.

Maia took fire this week for apparently attempting to rush through passage of a law that would reduce punishment for political parties taking suspect campaign donations.

Supreme Court Justice Gilmar Mendes, sometimes seen as less friendly than other judges to the Car Wash investigation, accused Congress of crafting a law that "will give impunity to political parties misusing public resources." Maia quickly backtracked.

David Fleischer, professor emeritus at the University of Brasilia, describes the situation in Brasilia as "waiting for the end of the world."

And "everyone's building firewalls," Fleischer said.