The future of Prime Minister Prayut Chan-o-cha hangs in the balance pending Wednesday's Constitutional Court ruling on the legality of his continued occupancy of an army residence since his retirement from the military.
A ruling against the prime minister would spell the end of his premiership, and also end the term of his current cabinet.
Opposition MPs led by the main opposition Pheu Thai Party lodged a petition with the Constitutional Court through parliament president Chuan Leekpai on March 9 after the issue was raised during the opposition's censure debate against the government on Feb 25-27.
In the petition, Pheu Thai accused the prime minister of a conflict of interest by continuing to occupy the army residence in Bangkok, in violation of Section 184 (3) of the constitution.
It said Gen Prayut, who is also the defence minister, should have vacated the building when he retired as army chief in 2014, and that by staying on free of charge, he had broken army regulations.
The prime minister and his family reside in the house in question located at the 1st Infantry Regiment, King's Guard, on Vibhavadi Rangsit Road in Bangkok.
After leading the coup that toppled the Pheu Thai-led administration on May 22, 2014, Gen Prayut retired as army commander-in-chief on Sept 30, 2014.
He remained prime minister and was returned to office following last year's general election.
The army has explained that the house the prime minister lives in is not a "welfare house" provided for top brass.
It was re-designated as a "visitor's house" in 2012. The army has also cited security as the reason why Gen Prayut needs to live inside the army compound.
Phichai Ratanatilaka Na Bhuket, a lecturer at the National Institute of Development Administration, told the Bangkok Post that he believed Gen Prayut is unlikely to survive the legal challenge.
He cited Section 184 which prohibits a conflict of interest by political-office holders.
Mr Phichai added that army regulations cited by Gen Prayut in his defence were not justified because the constitution overrides the regulations.
"If interpretation is based on the law, the prime minister would find it hard to survive. But if the case is interpreted according to the power structure in Thai society, he will stand a good chance of survival," Mr Phichai said.
If the court rules in favour of the prime minister, the court will likely come under criticism, no matter what the explanation, he said.
But if the court rules against him, Gen Prayut must leave office and parliament must find a new prime minister from the list of existing prime ministerial candidates such as Chaikasem Nitisiri of the Pheu Thai Thai Party or Anutin Charnvirakul of the Bhumjaithai Party, he said.
However, Mr Phichai said that Mr Chuan is also the favourite as he has gained recognition for his role in trying to foster reconciliation.
But if parliament still cannot find a suitable candidate for prime minister, it may resort to Section 272 of the charter, which opens the way for a non-elected outsider prime minister to be selected if the political impasse over forming a new government continues, Mr Phichai said.
Jade Donavanik, a former adviser to the Constitution Drafting Committee, told the Bangkok Post that he believed it is highly likely that Gen Prayut will survive the challenge.
The court is expected to take a "broader legal view" and rule in favour of Gen Prayut, based on army regulations that allow Gen Prayut who formerly served as army chief and has worked for the benefit of the country to continue to stay in the army house, Mr Jade said.
The Ratsadon (People's Movement) protest group earlier announced a rally outside the Constitutional Court today.
Pol Maj Gen Piya Tawichai, deputy commissioner of the Metropolitan Police Bureau, said on Tuesday that any demonstration in the court grounds would be illegal.
Three companies of police, behind barricades, would guard the court today, he said.
Another anti-government rally is planned at Lat Phrao intersection in Bangkok's Chatuchak district today.
The Facebook page of the United Front of Thammasat and Demonstration on Tuesdayinvited supporters to gather at Lat Phrao intersection at 4pm today.
Demonstrators packed the same intersection last Friday.