Prime Minister Srettha Thavisin may face suspension from duty if the Constitutional Court accepts a petition from a group of senators accusing him of violating a code of ethics over the appointment of a PM's Office Minister.
The court is expected to meet on Thursday to decide whether to accept the petition.
On Friday, 40 senators asked the court to rule on the status of Mr Srettha and PM's Office Minister Pichit Chuenban after the latter was appointed to the post in a recent cabinet reshuffle.
The petition, submitted via Senate speaker Pornpetch Wichitcholchai, asks the court if Mr Srettha and Pichit should be terminated from their positions under Section 170 (4) and (5) of the charter, which deals with the ethics of cabinet ministers.
According to a source at the court, judges usually meet on Wednesdays, but the upcoming Wednesday is a Visakha Bucha public holiday. So, the judges are expected to meet on Thursday instead.
If the court accepts the petition, judges may order Mr Srettha and Pichit to be suspended from duty pending a ruling, the source said, adding the pair will then have 15 days to submit their defence.
The appointment of Pichit -- an adviser to Mr Srettha who also served as ex-prime minister Thaksin Shinawatra's former lawyer -- as the PM's Office Minister also raises questions about his eligibility to serve as a cabinet minister.
This is because he served time in jail for contempt of court over an attempted bribery case when he represented Thaksin in a controversial land case back in 2008.
On June 25, 2008, the Supreme Court sentenced Pichit and two of his colleagues to six months in prison after they tried to bribe Supreme Court officials by handing them a paper bag containing 2 million baht in cash a fortnight earlier.
All three represented Thaksin and his ex-wife, Khunying Potjaman na Pombejra, in the Ratchadaphisek land case, for which Thaksin was sentenced to two years in prison in 2008.
Speaking during his trip to Italy on Saturday, Mr Srettha said once again that he had asked the Council of State, the government's legal arm, for legal advice on the appointment of Pichit before submitting the new cabinet line-up for royal endorsement.
A source in cabinet earlier said Pichit's imprisonment in the 2008 contempt of court case did not render him ineligible to be appointed as a cabinet minister. The conviction had long passed the required 10-year break between finishing serving a jail term and the appointment.
However, the question of whether Pichit meets the MP's moral and ethical standards as required in the charter is a different matter, according to the source.
PM's Office Minister Pichit Chuenban