It is too early to try and fix two controversial sections of the charter, Senator Wanchai Sornsiri said on Monday.
The amendments were suggested by the Future Forward Party (FFP) whose MPs said they will propose a motion to rectify two key sections in the new charter which justify the military regime's orders and permit senators 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 National Council for Peace and Order (NCPO). Section 272 permits senators to join the House of Representatives in voting for a prime minister.
Mr Wanchai said the charter should be left uncorrected because the two sections have nothing to do with helping the NCPO prolong its grip on power, as claimed by the FFP.
He explained that allowing senators to take part in selecting a prime minister exists in an interim clause of the charter with a time limit of five years.
After that, the senators will not have the role of choosing a premier and so the charter should not be deemed as an instrument for extending the regime's power.
"If [the NCPO] stays on and does what is right and beneficial for the people, I don't see any problem with that," the senator said.
By proposing to table a charter amendment motion, the FFP is simply trying to cause political disruption, Mr Wanchai said.
Earlier critics warned that the FFP's goal of amending the charter would be an uphill task because it needs substantial support from senators. All 250 senators were appointed by the NCPO.
During the parliamentary session last Wednesday, all senators, except Senate speaker Pornpetch Wichitcholchai who abstained, voted in favour of Prayut Chan-o-cha, who is also the NCPO chief, to remain as prime minister.
FFP secretary-general Piyabutr Saengkanokkul has said that these amendments are "the party's mission that must be done urgently".
Mr Piyabutr said the party will ask the people to join the campaign to amend the charter.