Politicians renewed their calls Wednesday for four cabinet ministers with executive posts in the Palang Pracharath Party to step down.
The calls followed the issuance of a royal decree for the general election, and came after PM's Office Minister Kobsak Pootrakul said that their resignations were imminent.
Key Pheu Thai member Somkid Chua-kong said the four ministers should have quit the cabinet immediately after they decided to enter politics as a sign of goodwill.
"Although there are no legal obligations for them to step down, political etiquette should be their guide, but this hasn't been the case," he said. "Taking an advantage of others isn't the right thing."
The former MP for Ubon Ratchathani said he doesn't expect anything from the four ministers at this stage and went on to accuse them of abusing their positions to get ahead in the polls.
"They can stay on until election day. Their actions don't matter any more," he said.
Veteran politician Chaturon Chaisang, a key member of Thai Raksa Chart Party, also called on the four to quit, saying the time had now come for them to do so.
He also took a jab at Prime Minister Prayut Chan-o-cha for his remark this week about his political future, saying the premier was trying to justify his position as well as the political party that he supports.
Mr Chaturon was referring to Gen Prayut's comment, in which he said if he decides to remain in politics, he would choose a party that was "dedicated, truly selfless, and determined" to lead the country to a better future.
Meanwhile, reacting to pressure for them to resign, Mr Kobsak said he and the other ministers will first hold talks to determine the appropriate time to resign.
Mr Kobsak, who is also the PPRP's spokesman, insisted they would announce their resignation simultaneously, after informing the prime minister of their decision.
When asked if the PPRP would approach Gen Prayut to become the party's prime minister candidate, he said the issue will be decided by party executives in due time.
After the royal decree on the general election was published, Deputy Prime Minister Somkid Jatusripitak invited Industry Minister Uttama Savanayana and Commerce Minister Sontirat Sontijirawong for a meeting that took an hour.
They refused to share the details of the meeting. Close aides of Mr Uttama and Mr Sontirat said both ministers were taking extra precautions on media interviews because the royal decree on the elections has been announced.
Mr Uttama is the leader of the PPRP, while Mr Sontirat is the party's secretary-general.
Wichian Chaowalit, registrar of the PPRP, said the party plans to unveil its list of candidates next week.
The party's prime ministerial candidate will be considered next, he added.