Just three months after being sworn in into his second term, Thai Prime Minister Prayut Chan-o-cha is facing questions over his legitimacy and is set to be grilled Wednesday by the opposition in a parliamentary debate on his and his cabinet's failure to recite the full oath of office.

The brewing political storm is being seen by analysts as a challenge to the existence of the new post-junta government that was ushered in following a general election in March. The election was aimed at cementing the political legitimacy of Prayut, a former army general, who seized power in a military coup in 2014.

The March election saw the return of Prayut amid widespread criticism and suspicion that his military junta had engineered the result in his favor. The prolonged controversy over the incomplete oath has only offered additional political munition to the opposition and critics to attack the Prime Minister's legitimacy.

By challenging the administration's very legitimacy, the opposition parties are "trying to wake Thai people up to the fact that this is not a democracy; this is simply the continuation of the junta by a different form," Paul Chambers, a political analyst, and lecturer at Thailand's Naresuan University, told VOA News.

What really happened?

It all began on July 16 at the swearing-in ceremony for the newly-elected government at the Ambara Villa in Bangkok's royal Dusit Palace.

While taking the oath before Thailand's King Maha Vajiralongkorn, Prayut and his 35 cabinet ministers pledged their loyalty to the monarch but omitted the last sentence, which included a vow to "uphold and observe the Constitution of the Kingdom of Thailand in every respect."

Nine days later, newly-elected lawmaker Piyabutr Saengkanokkul noticed the error in the oath and brought it to the attention of Chuan Leekpai, the Speaker of the House of Representatives at Thailand's Parliament.

Piyabutr, who has worked as a constitutional law professor for over 16 years, opined that the incomplete oath effectively nullifies the legitimacy of the Prime Minister and his entire cabinet. House Speaker Chuan added the issue to the parliamentary agenda as an urgent matter.

Opposition leaders allege that the omission – as it refers to the upholding and complying with the Constitution – puts into serious doubts Prayut's commitment to the rule of law.

On August 27, the Office of the Ombudsman concluded that by failing to recite the full oath of allegiance at the ceremony, the Prime Minister and his cabinet had breached the Constitution. Raksagecha Chaechai, secretary-general of the Office of the Ombudsman, argued that an incomplete oath could mean that all of the government's actions could be seen as unconstitutional.

Constitutional Court stays out

However, last Wednesday, in relief to Prayut, the Constitutional Court refused getting dragged into the controversy by claiming the matter remained in the domain of the Prime Minister, his cabinet and the King.

Rejecting a petition lodged by the Office of the Ombudsman urging the court to decide on the validity of the swearing-in, the court unanimously admitted that it was "not in its authority" to make a ruling on the oath-taking ceremony before the King, the Bangkok Post reported.

The court said "the oath-taking concerns an action which reflects a 'specific relationship' between the cabinet and the King and is considered a political issue under an act of government, stated in Section 47 of the organic law on Constitutional Court procedure."

"The court thus cannot accept the petition for consideration," it concluded.

Critics say they expected the judiciary to protect the new government from trouble. Pitch Pongsawat, an assistant professor of political science at Thailand's Chulalongkorn University, told VOA News he was not surprised by the decision from a court that has developed a reputation for siding with Thailand's royalist, pro-military establishment.

"It [the swearing-in] is unconstitutional," he said, "but [it] doesn't matter with this regime... Everybody knows that they will find a way out."

Opposition upbeat

Opposition chief whip Suthin Khlangsaeng said the court's rejection of the petition had not settled doubts, so parliament was still bound to go ahead with its planned debate on the oath-taking, the Bangkok Post reported.

Opposition leaders also saw a silver lining to the court's verdict as they had feared that a judicial review of the cabinet's oath could limit what could be said in the parliamentary debate on Wednesday.

"Now that the court has dismissed the petition, the debate can proceed without restrictions. We'll be able to scrutinize the matter, and the Prime Minister now has no excuse to avoid [answering the questions]," Suthin said.

However, Jade Donavanik, former adviser to the Constitution Drafting Committee, warned the debate may violate Section 112 of the Criminal Code on lese majeste, as the court had ruled the issue was between the King and the Cabinet.

Prayut, meanwhile, has accepted to be questioned by the Opposition and will attend Wednesday's debate, the Prime Minister's Office Minister Tewan Liptapallop said on Monday. The decision came after Prayut avoided three parliamentary sessions on August 7, August 14 and August 21.

Tewan, who is also a government whip, said Prayut has asked the Cabinet ministers to attend the debate, which will proceed without a vote. Tewan, however, didn't elaborate on whether the Prime Minister will respond to the Opposition's questions himself or assign other Cabinet members to do so on his behalf.

It remains to be seen if Wednesday's parliamentary debate, which local media reports indicate would run for over 14 hours, could decidedly settle whether Prayut emerges unscathed out of the intense political fight or the Opposition succeeds in delegitimizing his government over the botched oath.