NONTHABURI, April 6 (AFP) - Thailand's main opposition Pheu Thai party confirmed on Wednesday (Apr 5) the daughter of billionaire ex-premier Thaksin Shinawatra as one of its candidates to be prime minister in the country's upcoming election.

Paetongtarn Shinawatra, a 36-year-old with a jet-setting lifestyle and half a million Instagram followers, stands in stark contrast to her establishment rivals - current Prime Minister Prayut Chan-o-cha and his deputy Prawit Wongsuwan.

A sea of Pheu Thai supporters, wearing T-shirts in the party's signature colour red, tramped into a football stadium on the northern edge of Bangkok to see Paetongtarn anointed alongside businessman Srettha Thavisin and party strategist Chaikasem Nitisiri.

Paetongtarn, who has been campaigning energetically despite being eight months pregnant, said she relished the fight.

"It is going to be a challenge but we will go and communicate as much as possible," she told reporters.

The parties for the May 14 vote fall into two broad camps - those backed by Thailand's military and royalist establishment, and more reformist opposition groups with Pheu Thai at their head.

Chief among the military-friendly candidates are two former military generals - 69-year-old Prayut who came to power in a coup in 2014, and 77-year-old Prawit of the ruling Palang Pracharath Party.

Pheu Thai is riding high in the polls but may yet be blocked from seizing the top job by the kingdom's constitution, written in 2017 by the then-ruling military junta.

"Pheu Thai cannot win alone, country and people have to win together. So people should vote for their future with Pheu Thai," Paetongtarn said.