Small parties have accepted Prime Minister Prayut Chan-o-cha's invitation to a dinner this Thursday amid a warning the government cannot survive in parliament without their support.
The dinner invitation came after the premier held a similar get-together with bigger parties last week. No small parties were invited.
Several say they will attend the casual dinner party at the Rajpruek Club in Bangkok.
Thai Local Power Party leader Chatchawal Kong-udom said he will join the dinner although he was unsure if other party members would take part.
Peerawit Ruengleudlapak, a list MP for the Thai Rak Tham Party, said most small parties are likely to turn up.
A cabinet minister called him to extend the invitation from Gen Prayut. He insisted all small parties should be invited.
He and other small parties have prepared issues to be raised with the prime minister during the get-together. They have divided up their time and agreed each party should have between three to five minutes to speak about their issues.
Thai Rak Tham will discuss with Gen Prayut the bill to improve pensions for the elderly, which requires the prime minister's approval before it can go before parliament for deliberation.
Mr Peerawit said he also intends to have a heart-to-heart with the prime minister and impress on him the sentiment shared by some small parties that they are being overlooked. "I'll tell the premier outright that we are being ignored. This is the final year of the government [before its tenure expires in March next year].
"If Gen Prayut wants to stay on to complete the government's term, he must treat us better," he said.
The government's majority in parliament is receding after at least 18 MPs were expelled from the ruling Palang Pracharath Party (PPRP) for acting in defiance of the party. They have since defected to the Setthakij Thai Party and do see eye to eye with the government.
Rawee Matchamadol, leader of the New Palang Dharma Party (NPDP), said the dinner would provide a rare opportunity for small parties to air issues of concern.
A source said the Setthakij Thai Party is unlikely to be invited to the dinner. The party's key figure, Capt Thamanat Prompow, formerly the PPRP secretary-general, fell out with the prime minister.