Future Forward Party MPs will propose a motion during the House session next week to amend two controversial sections in the new charter which justify the military regime's orders and permit senators' rights to vote for a prime minister.
The two sections are Section 279 and Section 272.
Section 279 legally endorses the orders and actions of the NCPO. Section 272 permits senators to join the House of Representatives to vote for prime minister.
FFP secretary-general Piyabutr Saengkanokkul said the proposal for amendments is "the party's mission that must be done urgently".
The FFP, widely known for its stance against coups in general, has campaigned for the removal of those sections from the charter.
The mission was announced yesterday as the party marked its first anniversary.
The event was held at Thammasat University's Tha Phrachan campus which drew up to 2,500 attendants.
Critics have said the FFP's goal to amend the charter is an uphill task because it needs substantial support from senators to approve constitutional amendments.
Two hundred and fifty senators were appointed by the National Council for Peace and Order (NCPO).
During the parliamentary session last Wednesday, all senators, except Senate speaker Pornpetch Wichitcholchai who abstained, voted in favour of outgoing premier Prayut Chan-o-cha, who is also the NCPO chief.
Mr Piyabutr said he is aware the senators may not support the opposition parties but remains hopeful.
He said the party will ask people to join the campaign to amend the charter.
"We'd like to ask people to help us by signalling [a need for charter amendment] to the Senate," he said.
FFP leader Thanathorn Juangroongruangkit said many people are dissatisfied with the return of Gen Prayut Chan-o-cha.
He said Gen Prayut's victory was secured by votes from 250 senators appointed by NCPO.
"That affected and distorted the decisions of political parties," he said.
"We knew Gen Prayut would come back no matter what," Mr Thanathorn told a forum which was part of the yesterday's event.
