BANGKOK (Reuters) - Nearly five years after Thailand’s 2014 military coup, the populist movement that the army has overthrown twice in a decade is contesting an election on Sunday that its leaders say is rigged against it.

FILE PHOTO: Supporters of Pheu Thai Party attend an election campaign in Ubon Ratchathani Province, Thailand, Februray 18, 2019. REUTERS/Athit Perawongmetha

Yet, the Pheu Thai party linked to ousted ex-premier Thaksin Shinawatra, is hoping it can beat the system, just as the former telecommunication tycoon’s loyalists have won every general election since 2001.

This time, Pheu Thai has shifted strategy by dividing its forces to capture new votes and to seek a “democratic front” with other parties to overcome junta-written electoral rules that give a huge advantage to the party seeking to retain junta chief Prayuth Chan-ocha as prime minister.

Sunday’s election has 81 parties competing, but the race has shaped up as one between Pheu Thai and “democracy front” allies versus the pro-army Palang Pracharat party that nominated Prayuth as prime minister.

Polls indicate that Pheu Thai will again be the top vote-winner, and it hopes with its allies to make up the largest bloc in the 500-seat House of Representatives.

But that may not matter, because the new constitution written by the junta allows parliament’s upper house, the 250-seat Senate, to vote with the lower house to choose the prime minister - and the Senate is entirely appointment by the junta.

That means pro-junta parties need to win only 126 lower house seats on Sunday to choose the next government, while Pheu Thai and allies, who can’t count on any support in the Senate, need 376 - three-quarters of the total up for grabs.

Despite the disadvantages, Sudarat Keyuraphan, Pheu Thai’s main prime ministerial candidate, said a democratic front could keep the military from controlling the next government.

“I still believe in the heart of the people and we have seen election upsets in many places around the world,” Sudarat told Reuters in an interview.

“Now, they have created a new structure that enables them to hold on to power in a semi-democratic structure,” she said of the military. “So we have to tell people about this and to put an end to this once and for all.”

‘GET RID OF THAKSIN’

However, the complex rules governing the election make it all but impossible for pro-Thaksin parties to form a government on their own as they have in previous elections.

Since he burst onto the political scene in 2001, Thaksin has dominated Thai politics, inspiring devotion among his mostly rural supporters for his pro-poor policies and revulsion from mostly middle-class and establishment opponents who decry him as a corrupt demagogue.

The rivalry has brought intermittent violent protests over almost 15 years. Twice, the military has stepped in, the first time in 2006 to oust Thaksin after he won a second term and again in 2014 to topple a government that had been led by his sister, Yingluck Shinawatra.

Thaksin now lives in self-imposed exile to escape a 2008 corruption sentence. He is officially banned from politics but has been hosting a weekly podcast since January discussing global affairs and politics.

His son, Panthongtae Shinawatra, 38, has made cameo appearances at Pheu Thai rallies, bringing loud cheers in party strongholds in the north and northeast.

Worry that a pro-Thaksin party might yet again win the election was one reason why the post-coup constitution made changes giving the junta a strong say in who will be prime minister, said Titipol Phakdeewanich, dean of the faculty of political science at Ubon Ratchathani University.

“The establishment have had a strong determination to get rid of Thaksin once and for all,” Titipol told Reuters.

PRO-DEMOCRACY FRONT

While the rewritten electoral rules give junta leader Prayuth’s party an advantage in choosing the next government, they are by no means a guarantee.

In recent weeks, talk of a “democracy front” has gained ground, with speculation different parties in the House of Representatives might muster the 376 votes needed to choose the prime minister.

That strategy took a hit when Thai Raksa Chart, a key pro-Thaksin ally of Pheu Thai, was disqualified from the election this month.

The constitutional court ruled that the party had broken the electoral law by nominating the sister of King Maha Vajiralongkorn, as its prime ministerial candidate, crossing the traditional boundary between monarchy and politics.

Still, Pheu Thai has other allies - including Pheu Chart party and Pheu Tham - while politicians from the dissolved Thai Raksa Chart campaign for the democratic front.

Other parties like the youth-oriented Future Forward Party, while not seen as “pro-Thaksin”, could join forces to keep the military out of politics.

The leader of another main party, the Democrats, has also said he won’t support keeping junta leader Prayuth as prime minister, though it is unclear if the staunchly anti-Thaksin Democrats would join any front with Thaksin loyalists.

Even if they unite, it’s unclear whether anti-junta parties can muster enough votes, but Pheu Thai’s Sudarat said Prayuth’s declaration as a prime ministerial candidate has had a galvanizing effect.

“For 10 years the military has been acting as a referee,” she said.

“But now they have reveal themselves and have become a player so this could lead to a new end game ... now it is up to the people.”