The Pheu Thai (PT) Party is confident its prime ministerial candidate will win endorsement from parliament in the next PM vote, a party source said.
However, the source said that before the vote, things may take an unexpected turn, and Palang Pracharath Party (PPRP) leader and prime ministerial candidate Prawit Wongsuwon could emerge as the new prime minister, with the support of renegade MPs from Pheu Thai.
The source said that all eyes are on whether parliament president Wan Muhamad Noor Matha will on Tuesday issue a letter setting a date for the next prime ministerial vote. The voting session must be set three days in advance.
If the vote is to be held on Friday, the source said the letter must be issued by Tuesday.
The source went on to say that a team of Pheu Thai negotiators have now gathered enough support for its prime ministerial candidate, Srettha Thavinsin, from other parties.
The source said the senators are also likely to vote in his favour as Pheu Thai has turned its back on the Move Forward Party (MFP), whose policy to amend Section 112 of the Criminal Code, known as the lese majeste law, is opposed by the senators.
Prawit for PM?
But if the senators still refuse to vote for Mr Srettha, this means Pheu Thai is deceived and is being used as a springboard for Gen Prawit to become the next prime minister, the source said.
Some believe senators may not vote for any of Pheu Thai's three candidates but choose to support those from the "conservative" camp as it attempts to secure the premiership.
Anutin Charnvirakul, leader and prime ministerial candidate of the Bhumjaithai Party, or Gen Prawit, may benefit from this situation.
The other two Pheu Thai PM candidates are Paetongtarn Shinawatra, daughter of former PM Thaksin Shinawatra, and Chaikasem Nitisiri.
Srettha: May not receive Senate support
"If Pheu Thai decides to become a stepping stone for Gen Prawit, this will spell doom for it," the source said.
"Pheu Thai executives must make a wise decision as the stakes are high. During the campaign for the May 14 election, we promised that we would not work with the 'uncle' parties [referring to parties linked with military leaders involved in the 2014 coup]," the source said.
The "uncles" refer to Prime Minister Prayut Chan-o-cha, the former UTN chief adviser and its prime ministerial candidate, and Gen Prawit.
The source said Pheu Thai earlier cited "a unique political situation" as a reason to end rivalry among parties from opposite ends of the political spectrum for the sake of unity.
But the party should have mentioned this before the May 14 election so voters could decide whether they agreed with it, the source said.
"Speaking about the issue right now is like an excuse for doing all it can to form a government," the source said.
The source said that a group of 40 MPs from the PPRP earlier promised to vote for Pheu Thai's PM candidate, even though the PPPR has not yet announced a formal decision.
However, the red-shirt supporters still disagree with the idea of working with the PPRP because Gen Prawit remains the PPRP's leader, the source said.
The only way for Gen Prawit to become the leader of a new government with the support of a House majority is to poach renegade MPs from Pheu Thai, the source said.
"There has also been concern that if Mr Srettha's bid for prime minister fails in the next vote and Pheu Thai still cannot form a government, this can pave the way for an 'outsider prime minister' to be nominated," the source said.
Under the constitution, if a joint sitting of parliament fails to select a new premier from party candidate lists, Section 272 would trigger an alternative route.
In such a situation, half of the 750 MPs and senators can initiate a motion to suspend the rule requiring that PM candidates come from party lists, paving the way for an outsider to be selected.
Old guard vs new one
Sukhum Nuansakul, a political analyst and former rector at Ramkhamhaeng University, said he believed that Pheu Thai's PM candidate, Mr Srettha, would not get the support from the senators in the next prime ministerial vote.
"I don't think the candidate's PM bid will succeed because the senators are close to the old power group, and they will not vote in his favour," he said.
"Actually, their real aim is to help Gen Prawit secure the premiership. If things turn out this way, street demonstrations can be expected," he said. "The old power group wants Gen Prawit to become the next prime minister. They want to maintain the old political system and don't want any change."
"Pheu Thai knows about their purpose, but it still plays into the hands of the old guard when it comes to forming a government," Mr Sukhum said.
If the so-called uncle parties are part of the Pheu Thai-led government, Pheu Thai will lose credibility, he said.
"The current situation is a battle between the existing political establishment seeking to maintain the status quo and a new generation calling for change," Mr Sukhum said.
Asked whether it will be possible for Pheu Thai to come back to working with the MFP, Mr Sukhum said that this depends on a Constitutional Court ruling on parliament's rejection of the renomination of MFP leader Pita Limjaroenrat.
On Wednesday, the court is scheduled to rule on whether to accept for consideration a petition seeking its ruling on whether Mr Pita's rejected renomination is constitutional.
If the court rules in Mr Pita's favour, Mr Pita can be renominated, Mr Sukhum said.
Jatuporn Prompan, former chair of the red-shirt United Front for Democracy against Dictatorship, slammed Pheu Thai over its move to include the PPRP and the UTN as part of the coalition. "Such a move has left people baffled as to what is true or false regarding the formation of a government," he said.
During the election campaign, Pheu Thai leader Cholnan Srikaew, Ms Paetongtarn and Mr Srettha said the party would not work with the uncle parties, Mr Jatuporn said.
"Dr Cholnan said he would resign as party leader if Pheu Thai teamed up with those parties. How will he explain to the people?" he said.