Five members of the Democrat Party resigned and joined the Pheu Thai Party on Monday, saying the Democrats had broken their promise by supporting Prime Minister Prayut Chan-o-cha.
Prasert Thongnoon, a former Bangkok councillor, and four other district councillors from Bang Kapi were welcomed into the Pheu Thai fold by chief strategist Sudarat Keyuraphan and other senior party members.
Mr Prasert told reporters that under the helm of former party leader Abhisit Vejjajiva, the Democrats had stressed they would not support Gen Prayut .
But the party reversed its position by joining the coalition government, said Mr Prasert, a former Bangkok Metropolitan Administration (BMA) official and director of Bang Kapi district.
That did not sit well with him, so he decided to resign from the party.
Khunying Sudarat said Mr Prasert's decision would benefit Pheu Thai and voters, as he knew how to serve the constituency and how the BMA operates.
She said Mr Prasert's presence in the party would boost the people's trust in Pheu Thai.