Deputy Prime Minister and Defence Minister Prawit Wongsuwon said Wednesday National Council for Peace and Order (NCPO) members are qualified to serve as appointed senators.
Gen Prawit was responding to scepticism about his controversial proposal calling for a chamber of appointed senators to work for five years during the transitional post-election period.
The proposal, backed by Prime Minister Prayut Chan-o-cha, gave rise to speculation that NCPO members would be appointed to sit in the upper house to counterbalance elected MPs, provided the charter writing body agrees to include the proposal in a provisional clause.
"Why not? What's wrong with that? The NCPO members understand all these issues [of national significance]," Gen Prawit said. "I don't see anything wrong with that [NCPO members serving as appointed senators]."
Gen Prawit said he did not consider appointing NCPO members as senators as "a prolonged stay in power".
He said his proposed chamber of appointed senators would have a tenure of just five years during the transitional period.
But if the Constitution Drafting Committee (CDC) disagreed with his proposal, he could not do anything about it.
"We have to go for an appointed Senate in the transitional period. But if the CDC disagrees, they can come up with what they want. I'm asking for five years in the provisional clauses. Just five years," he said.
Gen Prawit said the appointed Senate would be instrumental in pushing the country forward by working with the House of Representatives.
He insisted the appointed senators would not jointly vote with the House of Representatives to select a prime minister. Appointed senators would concentrate on implementing reforms and national strategy.
He said Gen Prayut had already addressed concerns about the matter.
On Tuesday, Gen Prayut said the appointed Senate was needed to safeguard the new constitution so politicians would not "mess with it" after a general election. Gen Prayut said the appointed Senate should not be empowered to vote to select a prime minister.
Asked if the CDC would pay heed to the NCPO's suggestion, Gen Prawit said the proposal was his personal suggestion, not the NCPO's decision.
Hours later, Deputy Prime Minister Wissanu Krea-ngam "clarified" Gen Prawit's comment on NCPO members serving as senators, saying Gen Prawit did not mean the NCPO would be made senators by default.
"The NCPO members aren't prohibited from serving as senators. So it means they may or may not be senators, depending on the selection process," he said.
Mr Wissanu also said he had no idea who would appoint the new Senate, and Gen Prawit had no idea either.
He stressed the proposal has yet to be considered by the CDC and any comments were just speculation.
Also on Wednesday, CDC chairman Meechai Ruchupan said the committee had not received a formal proposal regarding the appointed senators.
Asked if he felt uneasy about Gen Prawit's proposal, he said: "Why should I feel uneasy about things that aren't here."
The CDC is in the process of revising the charter draft and is expected to submit the final version to the government by March 29.
The charter drafters are currently working on provisions dealing with public independent agencies.
Meanwhile, Mr Wissanu said a bill on peace-keeping tasks during the charter referendum at the end of July, which is being reviewed by the Council of State, is close to being finished. He said the bill is likely to be sent to the cabinet this Tuesday.