BANGKOK - Thailand’s progressive front runner for prime minister told supporters on Sunday he would “not step back” ahead of a parliamentary vote this week that will determine if he will lead the country.

Mr Pita Limjaroenrat’s pro-democracy Move Forward Party (MFP) netted the most seats at the May 14 election but there are no guarantees it will be able to form government or that he will become the premier.

MFP’s eight-party coalition has a total of 312 lower house seats.

However, it remains short of the 376 votes needed across both houses of Parliament to endorse Mr Pita for the top job.

He faces resistance from the military-appointed, 250-member Senate, due to his party’s controversial push to reform Thailand’s royal defamation laws, as well as plans to shake up business monopolies.

Meanwhile, outside Parliament, he is being investigated over claims he was ineligible to run for office since he allegedly owned shares in a now-defunct media company. Legislators are not allowed to own media shares.

Mr Pita said the kingdom faces a momentous day this week when both the upper and lower houses will vote.

“If you do not step back, I won’t,” he told hundreds of supporters gathered in the rain in central Bangkok.

“If we make the right decision and give Thailand a chance, our country will develop,” he told the crowd.

But if the decision was wrong, he said Thailand’s cycle of poor democracy would continue.

“I don’t know how long we will have to wait before the golden chance of July 13 will come again,” he added, referring to the date of the vote.

Mr Pita urged senators to remember “we’re all the people’s politicians”.

“My thanks to those that say they’re on the people’s side and siding with the people’s majority,” he said.

Following his speech, Mr Pita told reporters that he had found “closer common ground” with the senators.

“Hopefully, in the four days remaining we will be able to come to a consensus and move this country forward,” he said.

The United Thai Nation Party said last week that it was considering whether to put up a rival candidate against Mr Pita.

Caretaker prime minister Prayut Chan-o-cha, who came to power in a 2014 coup and formed a vast coalition government after the 2019 poll, sought re-election under that new party’s banner.

Political analysts say it would be technically possible for him to stay in power under a minority government with support from the Senate.

However, the election results were seen as a national rejection of Mr Prayut and rule by military-linked parties. AFP