Thailand’s reformist opposition has won the most seats and the largest share of the popular vote in the country’s election in a stunning rejection of nearly a decade of military and military-backed rule.

The progressive Move Forward Party (MFP) and the populist Pheu Thai Party were far out in front with 99 percent of votes counted, but uncertainty remains about whether they will form the next government since the 250 military-appointed members of the upper house also vote on the prime minister.

That means MFP and Pheu Thai will need to negotiate deals with many other parties in order to be able to form the next administration.

With 99 percent of preliminary results released on the Election Commission website, the progressive MFP, formed only in 2020, had a total of 148 seats — 113 directly elected and 35 from the party list, reflecting its overall national support.

Pheu Thai, linked to the billionaire Shinawatra family, had a total of 138 seats — 111 directly elected and 27 from the party list — with Bhumjaitai third on 70 seats.

The United Thai Nation Party of incumbent Prime Minister Prayuth Chan-ocha, who led the 2014 coup as army chief, was trailing in fifth with 36 seats.

Susannah Patton, who heads the Southeast Asia programme at the Lowy Institute in Sydney, Australia, said there was no doubt about the wishes of Thai voters.

“This is a clear vote for change that cannot be ignored,” she wrote on Twitter. “The lessons of the last 20 years of Thai politics show that if establishment forces try to subvert this result, it will only lead to more instability and polarisation.”

Some 500 lower house seats were up for grabs in Sunday’s election, with 400 directly-elected constituency seats and the remainder allocated according to a system of proportional representation.

‘We can work together’

MFP saw a late-stage surge in opinion polls and was banking on young people — including 3.3 million first-time voters — turning out in force to back its liberal agenda, including plans to weaken the military’s political role and amend a strict law on royal insults that critics say is used to stifle dissent.

As the results trickled in, the mood among party workers and supporters at MFP’s campaign headquarters was electric.

“Before the election, I was hoping we would get about 100 seats,” said supporter Phisit Krairot, a 33-year-old engineer was among the crowd in Bangkok. “But the real-time updates I am seeing today exceed my expectations already.”

Party leader Pita Limjaroenrat arrived to cheers and later said the party planned a procession around Bangkok’s landmark Democracy Monument. He is expected to address the media at 12pm (05:00 GMT) on Monday.

“It is now clear that Move Forward has gained the immense trust of the people and of the country,” he wrote on Twitter in the early hours of Monday morning.

Pheu Thai leader Paetongtarn Shinawatra offered congratulations to MFP on their election success, saying the party with the most votes would get to lead the next government.

“We are ready to talk to Move Forward, but we are waiting for the official result,” she told reporters in Bangkok.

“I’m happy for them,” she added. “We can work together.”

The election is the first in the country since enormous youth-led protests in 2020 that broke long-held taboos by calling for curbs on the powers of King Maha Vajiralongkorn, as well as an end to the military’s involvement in politics. The armed forces have staged 13 successful coups since 1932 and nine that have failed.

MFP has promised radical reforms to the monarchy and military, including amending Thailand’s strict lese-majeste laws.

The lese-majeste laws have been increasingly enforced since the 2014 coup. The vaguely-worded Article 112 carries a penalty of 15 years in jail and rights groups say it has been used to punish political activism.

Pheu Thai, aligned with Paetongtarn’s father, the self-exiled billionaire Thaksin Shinawatra whose removal in a coup in 2006 set off Thailand’s political turmoil, remains hugely popular among working-class Thai people. Despite Thaksin’s fall, parties linked to the telecoms tycoon have won every election since, including twice in landslides.

The party has declined to commit to amending the lese-majeste laws, saying they would instead table it in parliament.

Analysts expect weeks of horse trading before alliances are formed and a prime minister is chosen.

Parties must have at least 25 seats to nominate a candidate, who needs 376 votes across the two houses to become prime minister.

The Senate was appointed by the military government and is expected to vote in favour of parties or blocs allied with the military.

That could turn smaller parties, such as Bhumjaitai, led by incumbent health minister Anutin Charnvirakul, into kingmakers.

In the last election in 2019, Pheu Thai won the most seats, but it was Prayuth who emerged as prime minister as head of a 19-party coalition. His Palang Pracharat party, now headed by his deputy Prawit Wongsuwan — also a former general — had the second most seats.

The Election Commission is not expected to officially confirm the final number of seats won by each party in this election for several weeks.