The Move Forward Party (MFP) has vowed to use its Rayong by-election win on Sunday as a springboard for scoring a victory at the next general election.
Commenting on the unofficial by-election results in Constituency 3 covering Klang district on Monday, MFP leader Pita Limjaroenrat said the party's candidate, Pongsathorn Sornpetnarin, won 60% of the turnout.
According to the Rayong election committee, Mr Pongsathorn won the seat with 39,296 votes, beating the Democrat Party's Banyat Jetnajan who received 26,376 votes. In third place was Ruengchai Sombatphuthorn, from the Nation Building Labour Party, with 881. Of the 122,582 eligible voters, 56% turned out to vote at 207 polling stations on Sunday.
There were 899 spoiled ballots.
The by-election was held to fill the void left by Nakhonchai Khunnarong, also from the MFP, who resigned as an MP after a past conviction and prison term for theft came to light.
Mr Pita said Mr Pongsathorn raked in 11,000 more votes than Mr Nakhonchai, testament to the party's growing popularity in the province.
"We will build on this momentum. It will strengthen our resolve to campaign for votes to [eventually win] the next general election," he said.
Dr Banyat, the Democrat candidate, used Facebook to thank those who had voted for him.
He said that despite his defeat, he captured many more votes than in the May 14 general election.