"I have decided to vote for Move Forward," the 19-year-old Supawut said. "For too long we have compromised, trying to change the system gradually, but what Move Forward wants to do is to challenge the patronage system."

He is among the 3.3 million first-time voters, aged 18 to 22, that parties are trying to woo.

An emphasis on young voters comes three years after student-led protests rocked Thailand by challenging the military's longtime influence over politics and - in a shocking development - even questioned the role of the king in society, a subject previously deeply taboo.

Move Forward was not officially part of the student protests but some activists are running as party candidates and many are party workers.

Its progressive campaign platform incorporates many of the protesters' demands including, most controversially, amending a criminal law that makes insulting the king punishable by up to 15 years in prison.

Other protest demands that Move Forward has adopted include re-writing the constitution to limit the power of the military, scraping military conscription and replacing appointed provincial governors with elected ones.

A late surge in the polls for Move Forward and its youthful leader Pita Limjaroenrat, 42, shows that some of the ethos of the protests seems to have spilled into the wider electorate, tired of old divisions that have racked the country over the past nearly two decades.

Voters aged 18 to 26 make up about 14% of the electorate, but Move Forward has recently been polling at about 34%, indicating it is winning the support of not just the young.

"Now our supporters come from all groups," said the party's deputy leader, Nattawut Buaprathum. "This is an opportunity for us to be in government and truly represent the people."

But the party leading most polls, on about 38%, is another opposition party, Pheu Thai, founded by self-exiled billionaire former prime minister Thaksin Shinawatra, whose populist, pro-poor governments have been ousted in two military coups.

Thaksin's daughter, Paetongtarn Shinawatra, is Pheu Thai's leading candidate for prime minister.

'BATTLEGROUND HAS MOVED'

For some voters, Move Forward offers a new direction from the years of binary confrontation between the conservative establishment, with its networks of patronage, and Pheu Thai that has at times brought bloody turmoil.

Thitinan Pongsudhirak, a political scientist at Bangkok's Chulalongkorn University, said the new ideas championed by younger voters may be resonating more broadly and expanding Move Forward's appeal.

"The battleground has moved from populism to structural reform ... Move Forward have the new agenda," said Thitinan, noting that Move Forward and Pheu Thai were running neck and neck in many areas.

Parichat Intarakun said she had voted for the conservative former army chief and current prime minister, Prayuth Chan-ocha, in the last election but was switching her support to Move Forward.

"I will vote for Move Forward because the leader has a very good vision for Thailand," said the 45-year-old office worker.

"He is very clear about the direction he wants to take the country."

If Move Forward does well on Sunday, it could form a coalition with the Shinawatra forces and deny one-time coup leader Prayuth, who is running with one of several conservative parties, another term in power.

But it's not certain if any party would join Move Forward in coalition because its anti-establishment stance, especially its call to amend the royal insult law, makes it for many too combative and antagonistic towards the establishment.

"Bringing Move Forward into a government may be risky and shorten the government's term," said Suvicha Pau-aree, director of the National Institute of Development Administration think tank and polling organisation.

Another huge question hanging over the election is whether the military-dominated establishment will let the will of the people take its course in the establishment of a new government.

Under a constitution drafted by the military in 2017, the party that wins the most seats in the 500-seat House of Representatives could struggle to form a coalition because a 250-seat Senate appointed during military rule also votes for the prime minister.

While there are fears of a return to street protests if parties feel aggrieved, some young voters said they would not abandon hope in electoral politics even if establishment parties still hold power after the vote.

"It's all right, at least there's a party now that has these policies. It's a good beginning," said a first-time voter who gave her name as just May.