New army chief Gen Apirat Kongsompong is the focus of attacks by key Pheu Thai Party members after his controversial statement that he could not rule out another coup after the promised general election.
He said if the political situation warranted it, with renewed rioting and unrest, he could not rule out another military coup.
Outspoken Pheu Thai member Watna Muangsook branded the army chief an "authoritarian" who sees himself as being above the law by virtue of his position.
A threat to tear down the constitution is subject to criminal charges, he wrote on his Facebook account on Thursday.
- Earlier report: Army chief refuses to rule out fresh coup
Gen Apirat used a press conference at the Royal Thai Army headquarters on Wednesday to make his position clear.
"If politics does not result in riots, nothing will happen," the army chief said in reply to a question.
Mr Watana, an ardent campaigner against coups, said the army chief's remarks were ruining the investment atmosphere. There had been an economic decline after the coup staged by his predecessor, Gen Prayut Chan-o-cha, now the prime minister.
Jaturon Chaisaeng of Pheu Thai said Gen Apirat had caused economic and political damage to the country with his remarks, which eroded international confidence in Thai democracy and the future of Thailand, INN reported.
Mr Jaturon praised the commander-in-chief for keeping the army neutral by fending off political interference, but it remained to be seen whether he could keep that promise when he also sits on the National Council for Peace and Order. (continues below)
Anti-coup activists rally outside Bangkok Remand Prison, calling for the release of their colleagues, on July 15, 2015. (Photo by Patipat Janthong)
Defence Minister Prawit Wongsuwon came out to defend the army leader, saying Gen Apirat's stance would not spoil the move toward a general election currently promised for Feb 24 next year.
The army chief did not make political threats, but hoped for stability after the country goes to the polls for the first time since the military coup in 2014, Gen Prawit added.