Thailand's Constitutional Court has ordered Prime Minister Samak Sundaravej to step down for hosting a cooking show.
In a televised broadcast on Tuesday, the court said he violated the constitution by working with a private company and called it a conflict of interest.
But Mr Samak's party, the People Power Party, said it would re-elect him within the week.
Meanwhile, protesters vow to keep up a campaign that has paralysed the government.
The People's Alliance for Democracy accuses Mr Samak of being a puppet of Thaksin Shinawatra, who was ousted as premier by the army in a coup in 2006.
A BBC correspondent says the court's decision has been criticised as being politically motivated.
Mr Samak toured a meat and vegetable market on Tuesday before his weekly cabinet meeting.
At a pro-government rally on Monday evening, he vowed not to resign or call a snap election.