Thailand's ruling party on Friday named Deputy Prime Minister Prawit Wongsuwan as its candidate to be premier in the kingdom's upcoming general election.

The army-backed Palang Pracharath Party (PPRP) gave the 77-year-old former army chief the nod as unofficial campaigning gathers momentum -- although no polling date has yet been announced.

Prawit will run against incumbent Prime Minister Prayut Chan-O-Cha, who earlier this month announced he would lead the campaign for the recently created Ruam Thai Sang Chart -- in English, the United Thai Nation party.

Prayut came to power as army chief in a 2014 coup before cementing his position in a controversial election in 2019, and he and Prawit were close allies during the years of junta rule.

His popularity is in the doldrums and the kingdom is battling a sluggish economy struggling to recover from the pandemic, which hammered the key tourism sector.

PPRP launched Prawit's candidature at a low-key event in Bangkok that he did not attend.

"We unanimously proposed Prawit Wongsuwan to be the sole PM candidate of our party," PPRP deputy leader Paibul Nititawan told reporters.

The main opposition party, Pheu Thai, is expected to name Paetongtarn Shinawatra -- daughter of former premier Thaksin Shinawatra -- as one of its candidates for prime minister.

Billionaire tycoon Thaksin, ousted as prime minister in a 2006 coup, lives in self-imposed exile in Dubai to avoid corruption charges he has said are politically motivated.

While Pheu Thai is polling strongly, the current Thai constitution, which was drafted under junta rule, gives army-linked parties a strong advantage.