Academics have raised suspicion over a group of senators throwing their support behind constitutional amendments, saying there might be a hidden agenda behind their move.
Yuttaporn Issarachai, a political scientist at Sukhothai Thammathirat Open University, said it may be a political ruse by the senators rather than actually bowing to calls for charter amendments.
On Sunday, 60 senators formed a group calling themselves "independent senators", all of whom are civilians.
They set up a Line chat group to discuss charter amendments and voiced support for a proposal seeking to amend Section 272 of the constitution, in order to remove the Senate's power to choose a prime minister.
Section 272 allows the senators who were appointed by the now-defunct National Council for Peace and Order (NCPO) to join MPs in voting for a prime minister.
Mr Yuttaporn said it seemed the senators had agreed to back off on charter amendment issues but also wanted the charter to be reviewed section by section rather than allowing a charter-drafting assembly to be formed to write a new one.
He also said opposition parties were now split over the charter amendment issue.
While Pheu Thai and six other opposition parties want the charter-drafting body to be set up first before making any amendments, the Move Forward Party (MFP) wants to first remove the power of the Senate before proceeding with the formation of the new body, Mr Yuttaporn said.
"It is likely to be an attempt by the 60 senators to persuade the MFP and its supporters outside the parliament to become their allies to fight against Pheu Thai," he said. "It maybe a manoeuvre to deflect the student demonstrators' attention from the government and the Senate and turn them against Pheu Thai."
He added that Pheu Thai's version of a charter amendment was similar to the government's -- both are seeking to set up a charter-drafting body, differing only over how many members it would have and how it would be chosen.
Wanwichit Boonprong, a lecturer at the political science faculty of Rangsit University, said he believed the move by the 60 senators had a hidden political agenda. They are civilians, not from the military, and had benefited from being appointed senators, he said.
It is likely they planned to become part of the charter-drafting body through a quota of appointed members, Mr Wanwichit added.
"They pretend to have the good intention of supporting charter amendments,'' Mr Wanwichit said. "Their bargain may be that they agree to have their power to choose a prime minister removed in exchange for some of them retaining their Senate seats."
If those senators do become part of the new body, they will have a chance to ensure the current coup-appointed Senate remains until a new one is elected, he said.
One of the 60 senators, Kittisak Rattanawaraha, said the group would meet today to discuss the issue. "We agree there is no need for the Senate to choose a prime minister now," he said.
"If Gen Prayut wants to become prime minister for another term, he must do it by himself by seeking support from other MPs."