Kawinnart Takee, a Future Forward Party (FFP) MP for Chon Buri, has been suspended from party activities pending the result of an internal probe.
The FFP launched an investigation into Mr Kawinnart's conduct after he twice voted against the party in parliament amid reports that dozens of former poll candidates are leaving the FFP en masse.
FFP secretary-general Piyabutr Saengkanokkul said the committee on ethics and discipline, headed by Chamnan Chanruang, will start its investigation after tomorrow's by-election in Nakhon Pathom's Constituency 5.
The probe is focusing on Mr Kawinnart's decision to vote in favour of government-sponsored bills twice in a row.
The first was the executive decree to transfer army units to the royal command and the other the 3.2-trillion-baht spending plan for the 2020 fiscal year.
The FFP earlier resolved to reject the executive decree while it decided to abstain in the budget bill vote.
Mr Piyabutr defended the party's move against Mr Kawinnart, saying it tries to strike a balance between the freedom of MPs to exercise their judgement and the need for the party to present a unified front by having the MPs debate issues among themselves if opinions are split.
"If we let MPs vote whichever way they want without regard to party resolutions, what's the point of having a political party," he said.
Mr Piyabutr said the ethics committee will forward its findings to the executive board which will decide on actions to be taken against Mr Kawinnart. Until the probe is concluded, the Chon Buri MP will be prohibited from taking part in party activities, he said.
Based on party regulations, there are four possible courses of disciplinary action: verbal warning, formal warning, revoking certain benefits and expulsion, he said.
The FFP secretary-general also said the 2017 constitution is to blame for the undercurrents of dissent. He said the charter attached more importance to party-list MPs than constituency MPs.
Consequently, some constituency lawmakers in the FFP reportedly feel they are unappreciated and are thinking about breaking away to form their own party.
Mr Piyabutr dismissed rumours of a breakaway as baseless and were intended to undermine the FFP.
Meanwhile, Nipon Chamjaras, a former FFP candidate in Chon Buri's Constituency 2, said that he and several dozen former poll candidates are likely to tender their resignations as FFP members with the Election Commission next week.
He said the former candidates are frustrated over the way the FFP has changed since the general election, alleging that nepotism and favouritism are playing a role in the management of the party's affairs.
Mr Nipon also alleged that the party failed to pay heed to its ex-candidates after the March polls, charging that the FFP saw them merely as a tool to capture votes for party-list seats.
In a related development, FFP MP for Chiang Mai Srinuan Boonlue, who abstained in the vote on the executive decree, insisted yesterday she was not a political cobra and was willing to face an investigation over her actions.
