The Move Forward Party's (MFP) bid to form a governing coalition may not be plain sailing after a number of senators made it clear they will not support its prime ministerial candidate.
Under the constitution, the 250 senators appointed by the now-defunct National Council for Peace and Order (NCPO) are allowed to join MPs in electing a prime minister in parliament.
It will be the second and last time they will co-elect a prime minister after Sunday's election. In the 2019 election, they joined MPs in voting for Gen Prayut Chan-o-cha to become prime minister.
MFP leader Pita Limjaroenrat on Monday announced a plan to form a coalition government comprising five former opposition parties and one new party, with a combined 310 MPs and himself as prime minister.
Mr Pita made the announcement after the Election Commission declared the MFP as the winner of the most seats in Sunday's general election with 152 MPs -- 113 from constituencies and 39 from the party list.
He said he took the victory as a mandate from the people for his party to be the leader in forming the next government.
Mr Pita said he called Paetongtarn Shinawatra, a Pheu Thai prime ministerial candidate, and congratulated her for her determination during the campaign and invited her party to join a coalition.
Ms Paetongtarn, in return, congratulated Move Forward and said the media should be informed that the two parties had talked in the interests of transparency, he added.
The three other former opposition parties he had contacted were Thai Sang Thai, Prachachart and Seri Ruam Thai. The five parties won 309 MP seats combined.
Mr Pita said he was contacting Pen Tham, or the Fair Party, which had one party-list MP, to join the coalition. He said it was a party which had worked hard for peace in the three southernmost border provinces.
The six parties would have 310 MPs in total, enough to be a majority government, he said.
"We would form the government as soon as possible so that there will not be a political and economic vacuum. Please be assured that Move Forward will be fast and meticulous," Mr Pita said.
Asked whether Move Forward worried that senators would not vote in support of the coalition to meet the required 376 votes of endorsement for prime minister, Mr Pita said he was not concerned about it as the party has a mandate from the people.
However, Senator Jadet Insawang said that upon assuming the post of a senator, he took an oath to protect the constitutional monarchy.
"The MFP and Mr Pita once announced they would scrap Section 112 [the lese majeste law], which will affect the monarchy. This is unacceptable," he said.
"If the MFP gathers the support of 376 MPs [more than half of the 750 members of the Lower and Upper Houses,] there is no need to seek the Senate's support for [a prime ministerial candidate]. But if they only get 309, they'll have to.
"For me, if Mr Pita, the MFP's prime ministerial candidate, is nominated for a vote in parliament, he won't get my vote," Mr Jadet said.
Senator Kittisak Rattanawaraha said that the senators would look at the qualifications of any prime ministerial candidate nominated for a vote in parliament.
"One of the qualifications is that the candidate must be loyal to the country, religion and the monarchy," he said.
He went on to say that it is premature to comment on the makeup of a coalition government.
"Senators only consider how the country will be, whether problems, conflicts or protests will follow if they vote for someone to become prime minister. We have to look at several dimensions.
"The senators will make a decision in the country's best interests," Mr Kittisak said.
Another senator, Chalermchai Fuengkorn, said that any party that wins the most seats must gather the support of 376 MPs so they can nominate a prime ministerial candidate and bypass the Senate.
"If they can also bring some other parties, such as Bhumjaithai, into their coalition, the Senate will be rendered meaningless," he said. "But if they cannot gather enough support and some senators abstain from voting, their bid to form a coalition will fail."
Laddawan Tantivitayapitak, secretary-general of the Open Forum for Democracy Foundation (P-Net), called on all sides to respect the people's mandate in the poll and for the Senate to comply with the result of a majority vote by the House of Representatives to nominate a PM candidate.