The Pheu Thai Party on Wednesday welcomed former House deputy speaker Suchart Tancharoen into its ranks. He was formerly with the Palang Pracharath Party, which still leads the caretaker government.
Key figures of Pheu Thai were present to greet Mr Suchart, 65, when he arrived at the party's headquarters.
Pheu Thai leader Cholnan Srikaew said Mr Suchart was a nine-time representative of the eastern province of Chachoengsao. He was formerly a deputy interior minister and a deputy leader while member of the disbanded Thai Rak Thai Party, a previous edition of Pheu Thai. Thai Rak Thai was dissolved in 2007 over allegations of electoral fraud.
Mr Suchart and his group were with the Bhumjaithai Party before moving to Palang Pracharath.
On Wednesday Mr Suchart said that he felt comfortable joining Pheu Thai. It was like returning to his old home, which had supported his political career for over a decade, he said.