Small parties with 30 MPs between them will decide the government's fate in the censure debate, according to Pheu Thai Party leader Cholnan Srikaew.
For the government, small parties, many of them with one MP each, matter more than bigger parties, said Dr Cholnan, who holds the top post in the opposition block.
The coalition parties were left clinging to a thin parliamentary majority following the expulsion of 21 MPs from the ruling Palang Pracharath Party (PPRP).
The MPs belonged to the faction controlled by the former PPRP secretary-general Capt Thamanat Prompow who was among those purged.
Dr Cholnan also referred to a recent dinner party attended by big coalition parties and invited by Prime Minister Prayut Chan-o-cha. No small parties took part in the get-together.
The prime minister is separately meeting small parties over dinner on Thursday, and their acceptances of the invitation were more meaningful for the party's survival than the get-together of the big parties.
"The 30 MP seats which the small parties hold can make or break the government in the no-confidence debate," Dr Cholnan said. The opposition has said it will file a censure motion against certain cabinet ministers in May when parliament reconvenes its ordinary meeting.
The Pheu Thai leader said he was counting on the 30 MPs handing their votes of no-confidence against the government if they attached importance to national interest.
Meanwhile, government spokesman Thanakorn Wangboonkongchana criticised the opposition for trying to undermine unity.
He said the opposition should spend more time making sure the issues it planned to raise in the debate hold water.
Kathathep Techadetruengkul, a list MP for the Pheu Chart Thai, one of the small parties, said his party will attend and would raise issues of concern, including farm produce prices and social inequality.
However, Mr Kathathep insisted he will not be casting a vote of confidence if cabinet ministers cannot counter the allegations made against them in the debate.
