Key members of the Democrat and Pheu Thai parties have not ruled out the possibility of the two parties joining hands to prevent a non-elected prime minister from coming to power after the next general election.
The issue was raised at a seminar titled "National Reconciliation under the National Council for Peace and Order (NCPO)" held by the Thai Journalists Association (TJA) on Sunday.
While Democrat deputy leader Nipit Intarasombat said the prospect of the two parties working together after the election seems remote, it is still a possibility if they put aside their grudges.
"If we do not discuss [differences] peacefully, there is no way to keep the military at bay. All parties must join hands to form a government," Mr Nipit said.
According to the NCPO's roadmap, the next general election in the country is scheduled to take place by November next year.
Addressing the issue, Pheu Thai key figure Chaturon Chaisaeng said he believed any window of opportunity for the two parties to work together should not be shut if they want to keep a non-elected outsider from becoming prime minister.
"There is no use in declaring you will never work with the other party," Mr Chaturon said.
Also Sunday, Kanin Boonsuwan, a member of Pheu Thai Party's legal team, said having an elected prime minister versus a non-elected outsider premier will become a contentious issue during the next election, along with the bread-and-butter issues.
While some believe it will be difficult for any party to win more than half of the total 500 seats in the House of Representatives, Mr Kanin said some factors must be taken into account.
If there is little opposition to a non-elected outsider and candidates from political parties are mediocre, it will be difficult for a single party to win more than half of the House seats.
But if feelings against an outsider prime minister run high and candidates for prime ministerial posts are outstanding enough, it is likely that a single party will win a landslide victory in the poll, Mr Kanin said.
"The issue of an elected prime minister versus a non-elected outsider will be vital in the next election, along with the economic problems and national reform issues. These issues will be decisive factors that will determine who wins the election and forms the government," Mr Kanin said.
He said parties that support an elected prime minister should have at least 390 House seats to form a multi-party coalition government, though such a government would find it hard to run the country while being closely scrutinised by the opposition and independent organisations.
The new elected government will also be legally required to comply with the national strategy laid down by the NCPO, Mr Kanin said.
On the other hand, if parties that favour a non-elected prime minister fail to win less than 250 House seats, there will be no chance of forming a government led by an non-MP prime minister, Mr Kanin said.
Under the constitution, senators can join MPs in proposing a motion to suspend the rule requiring prime ministerial candidates to come from political party lists, paving the way for an "outsider" prime minister to be selected, if a prime minister cannot be chosen from the lists of candidates for whatever reason.
Such a motion requires the support of at least half of the number of both MPs and senators present at a session. Then, the support of at least two-thirds of both MPs and senators, or 500 of them, is needed to suspend the rule.
However, Mr Kanin noted a government with a non-MP prime minister should have the support of at least 390 MPs in the House if it is to run the country smoothly. A non-elected prime minister who has the support of slightly more than half the MPs in the House will find it hard to survive, he said.
Sunday's seminar also touched upon the issue of national reconciliation as participants criticised the regime for lacking sincerity in restoring unity.
Adul Khieuboribun, chairman of the 1992 May Heroes Relatives Committee, said he was invited to be part of a committee studying national reconciliation led by Anek Laotamatas, but the prime minister failed to pay attention.
Mr Chaturon said while the NCPO used political conflicts as justification to seize power, it has fared most poorly in restoring national unity. During the past three years, the NCPO has only created conditions for further conflict, such as by using the all-powerful Section 44, while the new constitution and laws organic to the charter will also lead to more conflicts in the future, Mr Chaturon said.
Many people may be satisfied with the peace and order prevalent over the past three years, which is the strengh of the NCPO, but the NCPO has maintained peace and order through suppression, Mr Chaturon said.
The army led by then army chief Gen Prayut Chan-o-cha staged a coup to seize power from the Pheu Thai-led government on May 22, 2014, saying it was necessary to bring the country under control.