Thailand’s prime minister has been suspended from office after the country’s constitutional court agreed to hear a petition brought by the opposition that argues he has exceeded his legally mandated eight-year term.

Prayuth Chan-ocha, who came to power in a military coup but has since refashioned himself as civilian prime minister, will be temporarily relieved of his duties while the petition is considered, the court said on Wednesday.

While analysts said the move was unlikely to unseat the Thai leader, who has ruled since deposing the government of Yingluck Shinawatra in 2014, the decision to accept the legal challenge raises the possibility of political upheaval ahead of elections expected by next year.

The dispute stems from a controversy over the duration and validity of the former strongman’s term in power, during which time he has disbanded much of the political opposition, curtailed civil liberties and suppressed student pro-democracy protests that sought to reform the monarchy, the country’s most powerful institution.

Opposition parties behind the petition argue that Prayuth’s administration began in 2014 as leader of a military junta, meaning he should not be eligible to continue serving as prime minister.

Supporters of Prayuth and his ruling Palang Pracharat party contend that his term should be counted from 2016, when he was anointed prime minister by a military council, or 2019, following an election that was carried out under a military drafted constitution.

Thailand is set to hold an election by March 2023, when Prayuth’s current term expires.

The constitutional court’s decision was first reported by local media on Wednesday. The court released a statement confirming it had decided unanimously to take up the petition and voted by a margin of 5-4 to suspend Prayuth’s duties in the interim. Prayuth has 15 days to respond, the court added. It did not specify when it would issue its ruling.

The court could find in favour of Prayuth, who also serves as defence minister, but a decision against him could prevent him from contesting the upcoming election and herald Thailand’s first transfer of power since 2014.

Punchada Sirivunnabood, an associate professor of political science at Thailand’s Mahidol University, expressed doubts that the court’s decision would spell the end of Prayuth’s political reign.

“There are a lot of people, especially the middle and upper middle class in the city, that still prefer Prayuth as the prime minister,” she said. “I think there will be some way to make him survive.”

Deputy prime minister and ruling party leader Prawit Wongsuwan, another ex-military chief and deputy chair of the former junta, is expected to temporarily take over Prayuth’s duties, according to local media.

The prime minister’s popularity has sagged recently, with a poll by the National Institute of Development Administration released this month showing that 64 per cent of Thais wanted him to step down when his term expired on Tuesday, counting from 2014. One-third of respondents backed waiting for a court decision.

Prayuth has also survived a series of no-confidence votes in parliament, where he has been accused of economic mismanagement, with the latest challenge last month.

Protesters converged for a second day on Wednesday at the Government House in Bangkok, which houses the prime ministerial and cabinet offices, to call for Prayuth to step down.

The Thai baht dipped 0.3 per cent to Bt36.04 against the dollar on Wednesday, after the central bank’s governor said there was “no need” for aggressive interest rate rises to combat inflation that hit 7.6 per cent last month. Thailand’s benchmark SET index edged up 0.1 per cent.

Additional reporting by Nang Uraisin in Bangkok