BANGKOK: The leader of Thailand's election-winning Move Forward Party met fresh obstacles in his prime ministerial bid on Wednesday, as a court suspended him as a lawmaker and rivals successfully scuttled his re-nomination in parliament.

U.S.-educated liberal Pita Limjaroenrat has an extremely difficult path to the top job and must overcome fierce resistance from a royalist military at odds with his party's anti-establishment ambitions.

After more than seven hours of debate on a challenge to Pita's candidacy before a planned parliamentary vote on Wednesday, lawmakers voided his nomination, with opponents arguing a motion for him to be endorsed as premier had already been rejected when he was defeated in last week's vote.

As the debate ensued, the Constitutional Court separately announced Pita had been suspended as a lawmaker over an allegation he violated election rules by holding shares in a media firm, taking on its second case against him in six days.

The suspension does not bar Pita from running for premier but it was not immediately clear whether his eight-party alliance would seek to re-nominate him, by filing a different motion.

The 42-year-old had told Reuters in an interview on Tuesday that he was expecting "pre-planned" obstacles, describing efforts by the establishment to stop him as like a "broken record".

Thailand has been run by a caretaker administration since March and 65 days have passed since Move Forward's stunning triumph over military-backed parties in a May election, in what was widely considered a clear public rejection of nine years of government controlled by generals.

"Thailand is not the same since May 14. We have come halfway from the people's victory and there is another half to go," a smiling Pita told the house as he acknowledged the court's suspension order, receiving fist-bumps and applause.

POWER STRUGGLE

Wednesday's drama was the latest twist in a two-decade battle for power between elected parties and Thailand's conservative military establishment, which has seen political bans, court interventions, two coups and huge, at times violent street protests.

A constitution drafted by the military after a 2014 coup and skewed in its favour ensured that Pita was blocked in the first vote by the junta-appointed Senate, which has served as a bulwark against elected politicians and can effectively torpedo attempts to form governments.

Hundreds of Pita's supporters gathered peacefully in Bangkok to protest against the efforts to stop him, some carrying signs denouncing senators.

"I feel angry. They didn't respect the people's will," said protester Wilasini Sakaew, 21. "They didn't listen to the voices of 14 million people."

The progressive Move Forward ran a disruptive election campaign in which they mastered social media to target and win over millions of urban and young voters, promising bold institutional reforms to upend the conservative status quo.

But its agenda has put it on a collision course with powerful, conservative interests, demonstrated by the legal cases against him and a determined effort by rival legislators from the outgoing, army-backed government to keep him at bay.

After the vote to void Pita's nomination, senior officials from Move Forward and alliance partner Pheu Thai said they would arrange a meeting to decide their next move.

The planned prime ministerial vote was expected to be Pita's last, having announced that he would step aside if he fails and let political heavyweight Pheu Thai field its candidate in a third round.

"It is now clear that in the current system, winning public approval is not enough to run the country," Pita posted on Instagram during the debate.