Brazil's lower house of Congress is due to vote Wednesday on whether President Michel Temer should stand trial for corruption -- and the deeply unpopular center-right leader is expected to survive easily.

The canny 77-year-old veteran of Brasilia's notoriously corrupt political scene has struck a confident tone ahead of the vote, painting himself as needed at the helm of the country's cautious recovery from a deep recession.

The first president in the country to face criminal charges while in office, Temer is accused of obstruction of justice and racketeering. He denies any wrongdoing.

For opposition deputy Jose Guimaraes, from the leftist Workers' Party, this is an opportunity to ditch Temer, who took over in 2016 from impeached president Dilma Rousseff.

"This government no longer has the moral, institutional or political conditions to keep governing," Guimaraes said.

However, a two-thirds majority is required in the lower house of Congress to have Temer's case sent to the Supreme Court. Anything less and the case will be dropped as long as he remains in office.

Just as occurred in August, when Congress threw out an earlier criminal charge, Temer's allies are expected to reject a trial.

- Temer 'will not fall' -

This time, "there could be a few more or a few less votes than the first time, but the president will not fall," a source in the presidency told AFP, asking not to be identified.

Ironically, what makes it easier for Temer is that many of those judging him in the lower house -- 185 of the 513 deputies -- are themselves targets of anti-corruption probes.

Critics say the president is also boosting his chances of survival through blatant vote buying, opening up the budgetary purse to give Congress members the projects back in their home states that will help their own causes.

"Despite the damage already suffered by this government, deputies looking for favors can benefit from it," said Antonio Queiroz, an analyst with DIAP, a congressional watchdog representing trade unions.

Some opposition deputies acknowledge they do not have the numbers to bring down Temer, despite his huge unpopularity with Brazilians.

However, they hope to obstruct the parliamentary session by preventing a quorum from being formed, delaying any vote clearing Temer.

As for Temer, he has promised to come out of the vote ready to "put Brazil on the rails" after a two-year recession that has seen many investors flee.

Market watchers say the most significant result of Wednesday's vote will be indications of how many deputies support the president's bid to cut the generous pension system.

Temer says the reforms are needed to tame a runaway budget, but the proposals are hugely unpopular with Brazilians.

After taking over the presidency in controversial circumstances following Rousseff's impeachment, Temer has never had any illusions about his public standing, and he is not going to run in general elections scheduled in October 2018.

He has record low ratings, with only three percent considering his government "good" or "very good," according to the latest opinion poll in September.

Source: AFP