Opponents of Srettha Thavisin say the prime minister could face serious legal problems after apparently referring to his party MPs' influences on police promotion - problems that could even include removal from the premiership and the stripping of his electoral rights.
On Thursday petitioner Srisuwan Janya said he would seek ask the National Anti-Corruption Commission to launch an ethical probe into Mr Srettha's speech during a meeting of Pheu Thai Party MPs on Tuesday.
Recent reports claimed he told the MPs that some of them had successfully pushed for the appointment of new police station chiefs while others were unsuccessful.
The speech violates Section 185(3) of the constitution, which prohibits MPs and senators from influencing the promotion or transfer of any government official, as well as Section 186 of the charter, which bars a minister from interfering with the work of government officials, Mr Srisuwan said. He planned to file his petition on Friday.
Wiroj Lakkhanaadisorn, list MP from the opposition-core Move Forward Party, said the recent speech amounted to a confession, and it was not difficult to identify the new police station chiefs who received the support and the politicians who gave it.
Regarding Prime Minister Srettha's insistence that some had misunderstood the speech, Mr Wiroj said inconsistency could undermine the reliability of the prime minister's speeches.
The opposition MP said that during vote campaigns, Mr Srettha had vowed to eliminate cronyism.
Somchai Srisutthiyakorn, former election commissioner, wrote on Facebook that the prime minister could be held responsible for violating several sections of the constitution. He cited Sections 185 and 186.
He also said the charter empowered the National Anti-Corruption Commission to investigate political position holders' exercise of authority that violated the constitution, and to seek relevant rulings from the Supreme Court's Criminal Division for Holders of Political Positions.
If the court accepts such a case for trial, a targeted person must be suspended from work. If the court finds the person guilty, the person will be removed from their position. They will also lose their right to vote for 10 years and the right to run for office for life, Mr Somchai said.
On Thursday Mr Srettha reiterated that he never interfered with the promotion or transfer of any police officer.
Deputy Prime Minister Somsak Thepsuthin was tight-lipped when reporters asked him to comment on Mr Srettha's controversail speech.