Pita Limjaroenrat, the prime ministerial candidate of the election-winning Move Forward Party, on Sunday told parliamentarians that failure to vote for his premiership would be unforgiveable affront to Thai democracy.
Meeting about 1,000 supporters in front of CentralWorld shopping centre in Pathumwan district on Sunday evening, Mr Pita said Thursday (July 13) would be a historic day when House representatives and senators would have a chance to return normality to Thai politics.
"In four days it will be July 13 when lower and upper houses will jointly decide what Thai politics will be in the next decade."
"With the right decision, Thailand will be second to none."
"A wrong decision that is against the resolution will maintain the political abnormality of the past decade. I do not know when a golden opportunity like July 13 will recur," Mr Pita said.
"Return normality to all people. Please do not miss this opportunity because people may not forgive and may lose faith in representatives and the parliamenty system. So, do not disappoint people," he said.
He praised some senators who promised to "vote in favour of the people's choice and coalition allies", referring to the eight coalition allies – including his Move Forward Party and the Pheu Thai Party – which nominated him as the next prime minister in the Thursday vote of the joint sitting of parliament. The eight coalition allies number 312 out of the 500 House representatives.
"This opportunity is a historic moment for Thailand, the return of normality to Thai politics. All the 750 members of the lower and upper houses have the chance to return normality to Thai politics so that Thailand can progress and catch up with the world," Mr Pita said.
He told the gathering of his supporters that he might not be a perfect prime minister, but he would be the most hard-working.
The constitution empowers senators to join House representatives in the vote for a prime minister at a joint sitting. The parliament consists of 500 elected representatives and 250 appointed senators.
To become prime minister, Mr Pita needs the support of a majority of the 750 members of the joint parliament - at least 376 votes. The eight coalition allies would need at least 64 more votes in the joint sitting on Thursday.
Many senators earlier said they could not support Mr Pita because his Move Forward Party planned to amend the lese majeste (royal insult) law.
Mr Pita's route to the premiership is also jeopardised by petitions against his eligibility for political office related to his past shareholding in iTV plc and other legal technicalities.
The constitution prohibits a shareholder of a media organisation from running in a general election.
The Election Commission is investigating whether Mr Pita violated Section 151 of the organic law on the election of MPs.
Under the Section 151, anyone who runs in a general election while knowing he is unqualified to do so is liable to a jail term of up to 10 years, a fine of up to 200,000 baht and a 20-year ban on his electoral rights.
Numerous previous election winners in Thailand have been barred from taking office or removed by court rulings.
In 2020, Move Forward's predecessor party Future Forward was dissolved after a ruling that a loan from leader Thanathorn Juangroonrungkit was a donation, and Mr Thanathorn was banned from politics for 10 years.