The Election Commission (EC) will consider whether to ask the Constitutional Court to rule on the legality of its method of calculating and allocating party-list seats.
EC chairman Ittiporn Boonpracong said the commission was studying laws that stipulate how the party-list MP seats should be distributed.
The laws are Section 91 of the constitution and Section 128 of the organic law governing the elections of MPs.
However, Mr Ittiporn said the commission has already come up with its calculation method, but it was awaiting final approval at an EC meeting due to be held shortly.
Asked by reporters if such a calculation method may breach the laws and whether it was necessary to seek a Constitutional Court ruling on the matter, Mr Ittiporn said that would be debated at the meeting.
Democrat Party executive Ramet Rattanachaweng said on Wednesday the EC should ask the Constitutional Court to have a final say on the calculation and allocation of the 150 party-list seats so the dispute over the issue could be laid to rest.
Major parties have come out in force to criticise the EC's method of calculating the party-list seats, saying it was designed to hinder large parties.
The EC had previously announced that 71,000 votes would translate into one party-list seat based on the March 24 turnout.
However, reports say a revised EC calculation method would make it possible for small parties which garnered between 30,000-40,000 votes each to earn at least one MP seat. As a result, at least 25 parties are eligible for party-list seats according to their share of the vote.
Somchai Srisutthiyakorn, a former Democrat Party MP candidate who formerly served as election commissioner, said earlier the calculation method must follow both Section 91 of the constitution and Section 128 of the organic law.
He insisted the required number of votes for one seat was about 71,000, and that any party with fewer votes would not qualify.
Mr Somchai said according to that process only 14 parties were eligible for party-list seats.
Gen Viddhavat Rajatanun, chief of the Office of the Ombudsman, said the office was in the process of considering whether to accept a petition calling for the nullification of the March 24 poll.
It was submitted by Ruangkrai Leekitwattana, a former member of the now-dissolved Thai Raksa Chart Party.
Citing inconsistencies in the vote count, the controversial calculation of party-list seats and uncounted ballots from New Zealand, Mr Ruangkrai said the EC's handling of the poll may not be constitutional.
He asked the Office of the Ombudsman to forward the case to the Constitutional Court for consideration.
Meanwhile, the Thai Academic Network for Civil Rights on Wednesday arrived at the EC and submitted a letter asking the commission to disclose the number of votes cast at each polling unit nationwide.
The group urged the EC for details on the way the seats are calculated.