The opposition plans to submit a motion by the end of next week calling for a censure debate, much of which it says will likely target Prime Minister Prayut Chan-o-cha and five core ministries.
Speaking after a meeting of opposition parties on Monday, Pheu Thai MP for Maha Sarakham Sutin Klungsang, the chief opposition whip, said one last meeting will take place tomorrow when the censure motion will be finalised and then submitted to the House of Representatives on June 15.
Despite saying preparations for the debate were about 90% complete, he admitted that it was still not certain how many cabinet ministers will be targeted.
So far the opposition is concentrating on Gen Prayut, as well as the Ministry of Finance, Ministry of Commerce, Ministry of Agriculture and Cooperatives, Ministry of Transport and the Public Health Ministry, said Mr Sutin. The number of cabinet ministers to be grilled at present will be between five and six, he said.
The debate will deal mainly with five main topics: the government's failure at public administration, corruption and cronyism, law and order, abuses of power, and a failure to adopt policies the government said it would upon taking office, he said.
Mr Sutin appeared reluctant to say how confident the opposition was about bringing the government down.
He said he expected some Pheu Thai Party MPs would vote for the government while some coalition MPs would likely vote against it.
"We're not hoping for anyone to help us [to vote against the government]. Instead, we aim to ensure that the quality of our argument will by itself win support from both MPs and members of the public," he said.
Government spokesman Thanakorn Wangboonkongchana, meanwhile, warned the opposition it had better be able to support the accusations it was considering making against the government with evidence.
It's typical of the opposition to brag about having information proving allegations against the government when in fact it doesn't have anything and lets things descend into mud-slinging, he said.
He was responding to a remark by Pol Col Thawee Sodsong, secretary-general of the opposition Prachachat Party, who had earlier told reporters he had evidence to prove the PM and some cabinet ministers were guilty of misconduct in several cases to be brought up in the debate.