Opposition Democrat Party leader Abhisit Vejjajiva yesterday insisted his party is determined to overthrow the "Thaksin regime", saying the government had lost legitimacy.
He said the Democrats are ready to support popular movements conducted within constitutional limits.
Abhisit did not rule out the possibility of party MPs quitting in order to conduct the campaign.
"If it leads us to win the battle, we won't hesitate [to do it] with unity," he said.
"The Democrat Party is inviting everyone to join us in reforming the party in order to reform Thailand. Our aim is to uproot the Thaksin regime. If we succeed, we in the Democrat Party will not accept any post arising through unconstitutional means," he said.
Abhisit was speaking after chairing an urgent meeting with the party's executive committee and MPs to discuss what role the party should play in the protests.
Some MPs joining in
A Democrat MP, who asked not to be named, said some MPs had decided to join the "anti-Thaksin regime" protests, which are being led by former Democrat MP Suthep Thaugsuban.