Srettha Thavisin of the populist Pheu Thai party has won the backing of parliament to become Thailand’s next prime minister, paving the way to a new coalition government and an end to weeks of uncertainty and political impasse.

Property tycoon Srettha’s victory, with 482 votes from the 727 politicians present on Tuesday, ends months of suspense, legal wrangling and horse-trading that followed the May elections.

The progressive Move Forward Party, which won the most votes in the national election, was blocked from taking power by conservative senators.

The vote came hours after the Pheu Thai party’s billionaire figurehead Thaksin Shinawatra made an historic homecoming after years as a fugitive in self-imposed exile.

Al Jazeera’s Tony Cheng, reporting from Bangkok, said Srettha had won a strong mandate.

“It is out with the old and in with the new. Srettha got over the 376 benchmark votes that he needed in both the lower and upper house. Interestingly he did that with more than 150 votes in the Senate, the Upper House, which is all appointed by the military,” Cheng said.

Political neophyte Srettha will be tasked with forming and holding together a potentially fragile coalition that will include parties backed by the military, which overthrew Pheu Thai governments in coups in 2006 and 2014.

Srettha will lead an alliance of 11 parties that includes two pro-military parties affiliated with outgoing Prime Minister Prayuth Chan-ocha, who led the 2014 coup. Move Forward is not part of the grouping.

Critics called the new government a betrayal of the election results, but Pheu Thai leaders defended it as a necessity for ending the political deadlock and creating reconciliation.

At Pheu Thai party headquarters, supporters in red danced in celebration.

“I will try my best and work tirelessly to improve the quality of life for Thai people,” Srettha said.

Pheu Thai excluded Move Forward, saying its commitment to changing the royal defamation law had made it impossible to rally enough support from other parties and the Senate.

Both houses of parliament vote together for the prime minister under the military-implemented constitution, in an arrangement designed to protect conservative military-backed rule.

‘Become more democratic’

Pheu Thai said it would control eight cabinet posts and nine deputy cabinet posts. The military-backed parties – Palang Pracharath and United Thai Nation – are to receive two cabinet posts and two deputy posts each. Pheu Thai has not identified the ministries that each party will control.

It said the coalition agreed to support Pheu Thai’s platform of boosting the economy, increasing the minimum wage and ending mandatory conscription.

They will also support the continued legalisation of medical cannabis and work to amend the constitution to make the country “become more democratic,” while not touching the royal defamation law, Pheu Thai said.

The parliamentary vote came hours after divisive ex-Prime Minister Thaksin Shinawatra returned to Thailand after years of self-imposed exile, mostly in Dubai.

His return was an emotional moment for supporters of the 74-year-old billionaire, who won the loyalty of millions with populist policies that directed attention, and funding, to poorer areas of the country’s largely rural north.

Thaksin and parties backed by him struggled with the military for years. Thaksin left Thailand 15 years ago, following a 2006 coup just a year into his second term, which sparked years of upheaval.

A Pheu Thai government led by Thaksin’s sister Yingluck Shinawatra was toppled in 2014 by then-army chief Prayuth.