(Bloomberg) -- About 51 million people are set to vote in Thailand’s general election after almost five years under a military government that’s now looking to bring its leader back as prime minister.

The junta chief, Prayuth Chan-Ocha, is backed by the royalist and military elite who have long dueled for power with exiled former leader Thaksin Shinawatra. Thaksin or his allies, who draw support from the rural poor, have won every election since 2001, only to be unseated by coups or the courts.

The contest between these dominant forces is expected to play out again in Sunday’s election. The poll is taking place under a military-backed constitution -- Thailand’s 20th -- that critics say gives appointed soldiers and bureaucrats the ability to stifle elected politicians.

The establishment is trying to extend and "legitimize its power" through the election and the constitution it enacted, said Punchada Sirivunnabood, an associate professor at Mahidol University’s Faculty of Social Sciences and Humanities near Bangkok.

A big turnout is expected in Southeast Asia’s second-largest economy, after Thais thronged ballot boxes in advanced voting last weekend. Polls open at 8 a.m. and close nine hours later, when counting begins. A 24-hour alcohol ban will be enforced from 6 p.m. Saturday.

Provisional results about the number of votes and constituency seats won by each party are expected on Sunday night. But clarity on who will form the government and become prime minister may not emerge for days or weeks until the tally is certified, after which parliament must sit to elect a premier.

Thailand’s establishment elites have tussled with Thaksin’s populist alliance for over a decade -- a fault line that could bring gridlock to the legislature. The run-up to the vote was among the most dramatic in Thai history as these divisions flared anew.

A Thaksin-linked party, Thai Raksa Chart, was disbanded earlier in March for hostility toward the constitutional monarchy, after King Maha Vajiralongkorn rejected the party’s nomination of his sister Princess Ubolratana Rajakanya as its prime ministerial candidate.

The dissolution by the Constitutional Court was seen as hampering Thaksin’s allies while bolstering Prayuth, who seized power in a 2014 coup when he was army chief.

The uncertainty around the election could weigh on the export and tourism-reliant economy, whose growth lags behind peers in the region. The poll also comes as Thailand grapples with risks from a surge in the baht amid slowing global trade.

Unsettled foreign investors have pulled out in excess of a net $700 million from Thai stock and bond markets this year.

Here’s some of our recent coverage ahead of this weekend’s election.

  • Exiled Billionaire Thaksin Shinawatra Haunts Thailand Election
  • The Thai Election Is Going to Test Asia’s Strongest Currency
  • Risk of Political Disarray Stalks Thai Economy as Election Nears
  • Thai Cyber Law Raises Fear Military Could ‘Cage’ the Internet
  • Distressed Rubber Lands Could Upend Thailand’s Electoral Map
  • Free and Fair? Dissolution of Party Adds to Thai Election Doubts
  • Race to Become Prime Minister of Thailand Is a Man’s World

To contact the reporter on this story: Siraphob Thanthong-Knight in Bangkok at rthanthongkn@bloomberg.net

To contact the editors responsible for this story: Sunil Jagtiani at sjagtiani@bloomberg.net, Ruth Pollard

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