BANGKOK (Reuters) - Thailand's general election set for May 14 will bring new faces into the fray but is likely to be over-shadowed by old animosity between the military-royalist establishment and popular opposition parties challenging the status quo.
The confrontation in the kingdom has shaped a tumultuous two decades of street protests, judicial intervention and coups that were quelled in recent years, largely by COVID-19 curbs, but could well play out again.
The main election contest will be between the rural-based political juggernaut founded by telecoms tycoon Thaksin Shinawatra, and the conservative, Bangkok-based political elite, dominated by pro-military forces that have ruled since the last coup in 2014.
The prospects of a democratic winner either standing up to the pro-military order, or working with it, will determine the political and economic trajectory of Southeast Asia's second largest economy, analysts said.
"In contemporary Thai politics since the 1990s, this is the most consequential election," Thitinan Pongsudhirak, a political scientist at Bangkok's Chulalongkorn University, told Reuters.
Leading the charge for the billionaire Shinawatra family is Thaksin's daughter, Paetongtarn Shinawatra, who has been campaigning hard in the vote-rich rural strongholds of the family's Pheu Thai party.
The 36-year-old, who is pregnant with her second child, has been drawing enthusiastic crowds and looks set to rekindle the kind of fervor that swept her father and aunt, Yingluck Shinawatra, to power in landslides.
Thaksin and Yingluck were toppled by the army in 2006 and 2014, respectively, despite overseeing economic growth. Both live in self-imposed exile to avoid graft convictions their allies say were aimed at preventing political comebacks.
While loved in the countryside and by working class voters, the Shinawatras are detested by many middle- and upper-class Thais who accuse them of cronyism to enrich business friends and buying off the poor with wasteful populist policies that unfairly burden urban tax-payers.
The Shinawatras deny the accusations.
Leading the conservative campaign is Prime Minister Prayuth Chan-ocha, a dour former army chief who led the last coup in 2014 and has ruled since.
The 68-year old royalist army man is running for the newly formed United Thai Nation Party and is appealing to conservatives with a promise of a steady hand and the slogan: "Have done, doing, and will continue".
Prayuth would appear to have his work cut out.
He came third in a opinion poll by the state-owned National Institute of Development Administration released on Sunday on who would make the best leader.
Not surprisingly, Paetongtarn came first followed closely by Pita Limjaroenrat of the progressive opposition Move Forward Party.
But it might not be the voters who decide who moves into Bangkok's Government House as prime minister.
An outsized influence in determining the next leader will be wielded by the 250-seat upper house Senate, which was appointed by the military government before the last election, won by Prayuth, in 2019.
The leader of the biggest party in the lower house after the election could be denied the top job if the Senate wanted to stymie them in a vote with minority parties in the lower house.
"One of the most important deciders of the election result is the power of the military-appointed Senate, which will likely side with the pro-military candidate," said Titipol Phakdeewanich, a political analyst from Ubon Ratchathani University.
In the past four years, the Senate has regularly voted to support the establishment, blocking legislation proposed by the opposition despite the approval of the elected lower house.
Paetongtarn, who warns voters of the dangers of coups setting the country "backwards", has spoken of the importance of a landslide victory in forcing the Senate to respect the vote. She has not said what she would do if her party won the most seats but was denied victory.
The Shinawatras' supporters have taken to the streets over the past two decades, as have their pro-military rivals, on occasion sparking bloody chaos when the army cracked down.
Authorities will also be keen to avoid the return of youth-led protests that began in 2020 with opposition to Prayuth's government but evolved into once-unthinkable calls for reforming the monarchy - traditionally considered the unquestionable cornerstone of Thai culture and authority.
Many of those young protesters have rallied to the Move Forward Party.
Both groups of opposition supporters have pinned hopes for change on the election, said Thitinan.
"Their grievances have not been addressed," he said. "It has been suppressed."
Another round of suppression that extends pro-military rule could stifle the country as it emerges from its COVID slowdown.
"If it brings back more or less the same kind of government, Thailand will see more signs of political decay and economic stagnation," Thitinan said.
(Reporting by Panu Wongcha-um and Panarat Thepgumpanat; Editing by Devjyot Ghoshal and Robert Birsel)