Mingkwan Sangsuwan has resigned as the leader of the New Economics Party following what he described as an "accomplished mission".
Once known as a master of marketing, Mingkwan tendered his resignation yesterday but it was not made public until today (Thursday).
The Election Commission president also doubles as the political party registrar.
He said he had been responsible for drafting the party's platform of a new economic system and selling the idea to voters in the run-up to the March 24 general election.
Other members of the party's executive team were responsible for different areas, including recruiting members, raising funds and general management, he added.
"Now that the election has been completed, I see it is a suitable time for me to resign as leader of the New Economics Party," Mingkwan said in his resignation letter.
The letter stated that Mingkwan would keep his party membership and his seat as a party-list MP.
Mingkwan's resignation came amid conflict within the party, as many of its election candidates were seeking payments from the party to cover their campaign costs. One source said the spending for each candidate ranged from Bt200,000 to Bt2 million.
Votes from those candidates enabled New Economics to win six seats from the party-list electoral system. The party failed to elect any constituency MPs.