
He said his decision was aimed at showing anti-government protesters who occupied the Government House how to work and help the country under the democratic system.
"To be under the democratic system, ones should be member of political party and solve the country's problems through the parliament,' he said.
Chaisit said former House Speaker Yongyuth Tiyapairat visited him recently to convince him to be leader of Pue Thai Party leader.
Chaisit said at first he decided not to enter the politics after retirement. But he changed his mind after seeing what People's Alliance for Democracy and protesters did.
"The current political situation clearly showed that some people did not play by the rules and did not protec their rights by democratic means," he said. He also urged the PAD to set up a political party to contest in an election.
On Thursday Puea Thai Party leader Suchart Thadathamrongvech said that he had resigned in order to allow the selection of another capable person to lead the new party.
Suchart, who is also finance minister, said he had tendered his resignation as Puea Thai leader on Wednesday, but he would remain as an ordinary party member.
"There have been many new party members with long political experience. I think it's time to allow one of these qualified people to take over the job," he said.