A provisional clause under Section 272 of the charter, better known as the "outsider prime minister" rule, is being touted as an alternative route if the political impasse over forming the next government continues.
Democrat member Thepthai Senapong, who has been pushing for a national unity government, said Section 272 should be invoked if the situation culminates in deadlock.
In such a situation, senators could join MPs in proposing a motion to suspend the rule requiring that prime ministerial candidates must come from party lists, paving the way for an outsider prime minister to be selected.
The motion requires the support of at least two-thirds of both MPs and senators, or 500 of them, to suspend the rule. Mr Thepthai said for this to take place, all parties will have to take a step back otherwise it will benefit the current government headed by Gen Prayut Chan-o-cha and the National Council of Peace and Order, who will remain in power until a new government is formed.
He said the proposal may look far-fetched at this stage, but political parties will begin to see it as a "real possibility" after the Election Commission endorses the result of the March 24 general election.
"If a coalition government cannot be formed, the pressure for all sides to come together will increase."
Meanwhile, Paiboon Nititawan, leader of the pro-regime People's Reform Party, has shrugged off concerns that a Palang Pracharath Party (PPRP)-led coalition commanding a small majority in parliament may not be able to push key bills into law.
Mr Paiboon said a thin majority will not be a problem for the coalition, should it form.
Under Section 270 of the charter, the Senate can join the Lower House in voting on draft laws, as well as approving and disbursing the budget, he said.
In another development, a source said Constitutional Court judges on Wednesdayfailed to reach a decision on the controversy over whether to accept an EC petition on how party-list seats are calculated and will discuss the matter again on April 24.
