The opposition is moving to file a no-confidence motion against the government next month -- the second such censure move against the current administration.
Sutin Klungsang, chief opposition whip and an MP for the main opposition Pheu Thai Party, said on Tuesday the debate would focus on the government's handling of the faltering economy and alleged corruption.
He insisted the opposition will pack a surprisingly heavy punch this time around.
Mr Sutin said the bloc was preparing the censure motion for submission to parliament next month. In the meantime, the opposition parties are compiling information to be used for grilling cabinet ministers to be targeted.
Although he declined to say who will be grilled, there are credible indications Prime Minister Prayut Chan-o-cha will be the number one target on account of his role as government leader, while Deputy Agriculture Minister Capt Thamanat Prompow may also be on the list of targets.
Mr Sutin said the opposition is seeking to censure the government over what it claims are a failure to correctly analyse the economic situation and "unforgivable" levels of corruption.
The previous no-confidence debate was at the end of February. Mr Sutin said he expected no repeat of the rift between the Pheu Thai and Future Forward, a fellow opposition party which has since been dissolved over a loan made by its leader.
Back then, Future Forward MPs complained that they were "cheated" out of their chance to speak by Pheu Thai which spared Deputy Prime Minister Prawit Wongsuwon, one of the key targets, from an intense interrogation.
Gen Prayut said he is unperturbed by the prospect of another such session.
Wisarn Techatheerawat, the Pheu Thai MP for Chiang Rai, said the opposition was compiling evidence to support the censure allegations.