Karn Kalptinan, a candidate from the ruling Pheu Thai Party, secured a decisive victory in the Ubon Ratchathani Provincial Administrative Organisation (PAO) chairman election on Sunday.
Unofficial election results indicate Mr Karn, also a former PAO chief, received 387,456 votes, significantly outrunning his competitors.
Independent candidate Jittawan Wangsuphakijkosol came second with 322,986 votes, followed by Sitthiphon Laohawanich of the main opposition People's Party (PP) with 138,837 votes.
Athipatai Kuisrimongkol trailed behind with 3,620 votes.
Mr Karn's supporters gathered late on Sunday at the Kriang Kalptinan Law Office in Ubon Ratchathani's Muang district to celebrate the win.
Kriang Kalptinan, Mr Karn's elder brother, congratulated him with a garland of lowers and thanked the campaign staff and voters.
He emphasised the importance of completing unfinished projects to develop the province and praised former prime minister Thaksin Shinawatra's influence in rallying support for him.
Mr Kriang credited his brother's victory to the grassroots efforts and his dedication to community development over the past four years.
He said Mr Karn once in office will push policies aligned with Pheu Thai's national agenda, including the 10,000-baht cash handout scheme and promote welfare for the elderly.
"I feel proud that the people of Ubon Ratchathani have consistently valued our work," he said.
"I firmly believe in the continued support of the public to allow us to carry on with our work," he added.
Mr Sitthiphon and PP key party figures, including party executive Phicharn Chaowapatanawong, yesterday released a statement conceding defeat in the election.
However, the party said the poll outcome shows its support base in Ubon Ratchathani has grown since last year's general election.
Mr Sitthiphon urged the PAO leader-elect to consider adopting some of the PP's proposed campaign policies.
The party reiterated its commitment to grassroots politics, highlighting its plans to field candidates in 17 provinces in the PAO elections early next year.
