Ninety-nine MPs from 13 parties, including some in the coalition, signed a motion to amend the constitution so that 250 senators won't be able to vote on a prime minister.
Move Forward Party leader Pita Limjaroenrat and Democrat Party MP for Trang Sathit Wongnongtoey on Tuesday jointly submitted the motion to House speaker Chuan Leekpai, in his capacity as Parliament president.
The law requires a motion can be submitted by at least 98 MPs.
The motion repeals Section 272 of the 2017 constitution, which allows the 250 senators handpicked by the National Council for Peace and Order to vote alongside MPs in choosing a prime minister.
The section is part of the interim provisions in the 2017 charter which are in force for five years after the charter took effect, or until 2022. Move Forward had said earlier scrapping it was the first step to "switch off" senators before a new constitution could be rewritten. It fears if the prime minister resigns or dissolves the House while the charter rewriting is not yet finished, the current group of appointed senators would continue to vote alongside MPs in choosing another PM, further frustrating the will of people for another four years, it said.
Mr Chuan said on Tuesday the motion would be checked and then put on the meeting agenda within 15 days. It will likely be deliberated during Sept 23-24, together with two other versions of the same bill submitted earlier by Pheu Thai, the larest opposition party, and coalition parties.
Mr Pita said the 99 MPs came from 13 parties but not Pheu Thai or Palang Pracharath, the core coalition party. Bhumjaithai Party MPs were among those who signed their names on Move Forward's motion.
Mr Pita said he was confident that the amendment would be considered on Sept 23-24 and that no senators would block the bill, as all sides agreed that the section should be removed to allow the country to move forward.
Mr Sathit, the Democrat MP, said the amendment would focus on the issue of the Senate’s power to choose a prime minister. He said his party allowed a free vote on the issue although most of his fellow MPs had earlier signed to support the coalition's bill, which does not touch provisions on senators.
Mr Sathit said removing the section would end the automatic succession of power by coupmakers. He and other Democrat MPs would explain their decision at the next party meeting. He also believed the party leader would support them since he had previously backed the move to repeal Section 272.
Move Forward secretary-general Chaithawat Tulathon said that after the removal of the section, the process of choosing a prime minister would go back to what was specified in the constitution when interim provisions were no longer in effect.
Parties would propose nominees from their respective lists submitted to the Election Commission before an election. MPs then elect the prime minister by a simple majority vote from the lists. Only when the House could not choose the prime minister from among themselves can an outsider be proposed as a candidate, said Mr Chaithawat.
Apart from the three bills on constitution amendments in Parliament now, Internet Law Reform Dialogue (iLaw) has asked 50,000 people to sign up for what it calls people's version of the bill as allowed constitutionally. If the number is reached, its version will be submitted to Parliament for consideration as well. As of Tuesday evening, it still needed the support another 7,500 people to reach the required 50,000.