The court has played a key role at important moments in the upheavals that have convulsed Thai politics over the last 20 years, cancelling general election results in 2006 and 2014.
“I would not be surprised if the verdict of the Constitutional Court would be in favour of Prayut,” political analyst Napisa Waitoolkiat at Naresuan University told AFP.
Such a decision, anticipated by many, could see him remain prime minister until 2025 or 2027 – if he and his Palang Pracharat party can win re-election.
The kingdom is experiencing one of the lowest growth rates in the region, with the resumption of international tourism failing to lift the economy from the doldrums.
“Uncle Tu”, as Prayut is known, has never enjoyed widespread popularity, and Thailand’s years-long economic battering has only exacerbated a public sense of stagnation.
Earlier this year, the kingdom’s royalist-military elite were spooked when Chadchart Sittipunt, an ex-minister of the opposition Pheu Thai party, won a landslide victory in the Bangkok governor election.
With a general election due by March next year, the prime minister’s dismal popularity – with the candidate linked to him taking only eight percent of votes – is setting off alarm bells for his own MPs.
“If you see the behaviour of these politicians, they are not paying attention to the government now. They are more concerned about the next election,” political analyst Waitoolkiat said.
A recent National Institute of Development Administration survey found two-thirds of 1,300 people polled wanted Prayut gone immediately.
Protesters are expected to hit the streets from Tuesday evening demanding Prayut quit, and police have already placed shipping containers to protect streets around government buildings.
But Prayut rode out months of street protests in Bangkok in 2020 and has survived four no-confidence motions in parliament. Many believe he is determined to stay on to host the high-profile APEC summit in Bangkok in November.
At a small gathering Sunday, students and anti-government groups promised action against the “tyrant” Prayut and in a statement urged people to “view the upcoming election as a turning point in our fight”.
“Ball”, a student who gave only his nickname, said he believed Prayut would likely continue as prime minister, backed by the courts – and Thais may take to the streets once again.
“During the past eight years, nothing has improved in this country, and people are almost at their breaking point,” he said.