The opposition claims it has at least five issues on corruption to censure the government on next week, which it believes could well result in the disintegration of the coalition, chief opposition whip Sutin Klungsang said.
He added that the opposition is 95% ready for the Feb 24-26 debate with the speakers mostly being new faces, he said, adding that though some issues are familiar, the debate will still spring some surprises.
"The public is likely to learn that the issues are a great deal more serious than they thought," he said.
The allegations will target specific ministers, which may pressure coalition parties to consider whether they should remain in the government, the opposition whip added. He said history may repeat itself, citing the collapse of the first Chuan Leekpai administration in 1995 after the Palang Dharma Party, disenchanted by alleged graft in the land-reform programme, pulled out of the coalition.
When asked, Mr Sutin admitted one the issues concerned the planned relocation of the Tobacco Authority of Thailand's factory in Bangkok in favour of a certain business.
He also admitted that the opposition may lose some debaters if the Future Forward Party (FFP) is dissolved by a court on Friday. At least three FFP executives, who are also MPs, have signed up to speak in the debate. The FFP risks dissolution over money it borrowed from its party leader. If dissolved, its executives will lose their political rights.
Mr Sutin said that though the opposition knows it will not be able to defeat the government due to a lack of a majority, it is counting on revealing facts on mismanagement, which should pressure the government.
Separately, Anudit Nakhontap, secretary-general of the Pheu Thai Party, said the government appears to be nervous judging by its plan to set up "war rooms" to help with the defence of PM Prayut Chan-o-cha and five other cabinet members.
However, Digital Economy and Society Minister Buddhipongse Punnakanta denied these war rooms were designed to protect the censure targets, saying they were only to prepare information for ministers and the media to prevent distortion.
Apart from Gen Prayut, his deputies Prawit Wongsuwon and Wissanu Krea-ngam, Interior Minister Anupong Paojinda, Foreign Minister Don Pramudwinai as well as Deputy Agriculture and Cooperatives Minister Thamanat Prompow will be targeted in the debate.