The Future Forward Party (FFP) has petitioned the House speaker to ask the Constitutional Court to rule on whether 30 rival MPs should be disqualified for breaching media shareholding rules.
Most of the MPs are in the pro-regime Palang Pracharath Party (PPRP).
The petition was submitted at the new parliament complex on Kiakkai Road by 80 FFP MPs yesterday.
They say the 30 MPs are likely in breach of charter rules that bar owners or shareholders of media companies from applying to be MPs. They also demanded the Lower House examine the qualifications of prime ministerial candidates ahead of today's vote.
FFP secretary-general, Piyabutr Saengkanokkul, said the petition invokes Section 82 of the charter, which states that if one-tenth of all MPs raise a petition with the House speaker, he is obliged to forward it to the Constitutional Court for deliberation.
He said the party had found that many MPs held shares in companies whose declared businesses involve ownership of media outlets.
Of the 30 MPs listed, 27 were in the PPRP and the others were from the Ruam Palang Prachachart Thai, Pracha Piwat and Chartpattana parties.
"The section states the House speaker has no authority to rule on the matter but has to forward it to the Constitutional Court," Mr Piyabutr said.
The move comes after the Constitutional Court two weeks ago suspended FFP leader Thanathorn Juangroongruangkit as an MP pending its ruling on whether he breached media shareholding rules.
The Election Commission, which forwarded the case to the court, said the FFP leader held shares in the V-Luck Media Co when he registered as an MP candidate in early February.
Mr Piyabutr said if the same standard is applied, the Constitutional Court should accept the FFP case for consideration and order that these 30 MPs be suspended.
In another development, FFP MPS said there have been attempts to draw "cobras" -- renegade politicians to jump ship from the opposing political parties -- with tempting offers up to 120 million baht to the pro-junta side.
According to party spokeswoman Pannika Wanich, "When we refused their initial offers, they tried to convince us that our party will likely be disbanded or our leader Thanathorn imprisoned. They even made direct and indirect death threats".
Taopiphop Limjittrakorn, an FFP MP for Bangkok, said he was made a series of offers that peaked at a total of 120 million baht.
"I was offered the highest rate last week. However, I rejected these offers because I represent the people and their expectations which are worth more than 120 million baht."
Ms Pannika also warned that, "Parties which are involved in luring cobras will be disbanded if there is evidence linked to executives. It is also possible to take legal action against cobras and agents under Section 46 of the political party law".