Rungrueng Pittayasiri became the first executive member of the controversial Thai Raksa Chart party to tender his resignation from the party.
He however denied any involvement in last week's nomination of Princess Ubolratana as a candidate for prime minister. His resignation has been approved by the party on February 4.
On February 8, Thai Raksa Chart gave the Election Commission (EC) Princess Ubolratana's name as its sole PM candidate. However, in the evening, His Majesty the King issued a nationally broadcast statement that said it was against tradition and was unconstitutional for a member of the Royal Family to be involved in politics.
After the February 8 political earthquake, the future of the party, which has close ties with fugitive ex-PM Thaksin Shinawatra, was on the verge of being dissolved.
Rungrueng said the resignation was aimed to underline his innocence in the nomination.
"I'm a technocrat who is responsible for drafting the party's policies and have no expertise in selecting a prime minister," he said.
Another reason was that his family did not want him to work in politics.
He was speaking after handing his resignation letter to a representative of the EC.
His resignation from the executive board and the membership were endorsed by the party's registrar Chayika Wongnapachan on February 4.