Mingkwan Sangsuwan, the former leader of the New Economics Party (NEP) who joined the ruling Palang Pracharath Party (PPRP) on Tuesday, faces a challenge from key figures within the party over its choice of prime ministerial candidates.
Rong Boonsuaykhwan, a PPRP MP for Nakhon Si Thammarat, insisted any decision regarding the party's nomination of prime ministerial candidates must be decided on at a meeting of the party's executives, not just by making comments at a press conference, as Mr Mingkwan did on Tuesday.
"What Mr Mingkwan aimed to do after joining the PPRP was self-marketing," said Mr Rong.
Mr Mingkwan's press conference comments have been understood that he thinks he will be nominated as a party prime ministerial candidate.
Mr Rong claimed he had asked PPRP leader Prawit Wongsuwon about this matter, and he was told the process to decide who would be nominated had yet to begin.
He also quoted Gen Prawit as saying the fact that there are too many people seeking nomination is causing headaches for the selection committee.
"As for another claim by Mr Mingkwan that Prime Minister Prayut Chan-o-cha is to leave the PPRP for a new party, I understand the real motivation behind this statement is nothing but an intention to woo young voters who might not like Gen Prayut," Mr Rong said.
The remark will harm the party's popularity in the southern constituencies where most party supporters favour Gen Prayut, Mr Rong added.
"Anyone who aims to become a PPRP executive, or even gain nomination as its prime ministerial candidate, needs to be calm, charismatic and decisive, and can listen to the opinions of all sides," he said.
According to a source, Mr Rong discussed the issue with Gen Prawit by phone earlier, and it was Gen Prawit who authorised his explanations to the media. The party's deputy director, Veerakorn Kamprakob, said the news broken by Mr Mingkwan surprised key party figures. However, Mr Mingkwan could have been spot on.
Former prime minister Thaksin Shinawatra, meanwhile, said on Facebook that he believed Mr Mingkwan had already clinched the deal to be nominated as a second prime ministerial candidate after Gen Prawit before he decided to move to the PPRP. Thaksin said he knew Mr Mingkwan too well for it to be otherwise.