Padipat Santipada has admitted he wants to keep the post of House deputy speaker and that one way of doing that is to be ejected from the Move Forward Party, which would allow the MFP to take up its role of opposition leader in the parliament.
Mr Padipat said the issue would be made clear after the MFP elects a new leader and executive board on Saturday.
The changing of the guard was made necessary by the recent resignation of Pita Limjarorenrat as MFP leader.
Mr Pita, who was suspended from parliament pending a court ruling in his media share-holding case, said he stood aside so the party could elect a replacement who could also be the leader of the opposition. Party secretary-general Thawatchai Tulathon is likely to succeed him.
However, MFP cannot lead the opposition as long as Mr Padipat remains a member of the party and retains the job of deputy speaker. Mr Padipat is a constituency MP for Phitsanulok.
Under Section 106 of the charter, the opposition leader is appointed from the biggest party not in government. Its MPs cannot serve as cabinet ministers or as the House speaker or deputy speaker.
With Mr Padipat currently serving as first deputy speaker, the MFP cannot legally lead the opposition camp despite commanding the largest number of seats, 151.
To sidestep this restriction, the MFP is said to be considering expelling Mr Padipat, to enable him to move to another party and remain deputy speaker and freeing the MFP's new chief to serve as opposition leader.
The one-MP Fair Party, closely aligned to the MFP, has said it would take in Mr Padipat if he is purged.
On Wednesday, Mr Padipat admitted that his expulsion from the party was being considered as an option.
"I can't expel myself from the MFP, but it's certainly one of many options being entertained," he said.
If Mr Padipat were ejected from the MFP, he would have 30 days in which to join another party. He has reportedly discussed the issue with the Fair Party.
Sources said Apichart Sirisunthorn is likely to elected secretary-general and Parit Watcharasin the party spokesman at the MFP's general assembly on Saturday. Both men are list MPs.