Supporters of Yingluck Shinawatra’s government are gathering in western Bangkok for what they are calling a rally in support of Thailand’s democracy.
Earlier this week, a court ordered PM Yingluck Shinawatra and nine ministers to step down.
Thousands of police are on standby as opposition protesters are also planning a march in the capital.
Yingluck Shianwatra’s removal came after six months of protests which have unnerved investors and reduced tourist numbers.
Thailand has faced a power struggle since 2006, when Yingluck Shinawatra’s brother, Thaksin Shinawatra, was ousted as prime minister by a military coup, accused of corruption and abuse of power.
Their Pheu Thai party has a strong base of support with rural voters. Its supporters are known colloquially as “red shirts”.
Opposition supporters – dubbed “yellow shirts” – tend to be urban and middle class. They have been protesting against Yingluck Shinawatra’s administration for six months, occupying official buildings and disrupting elections in February.
Yingluck Shinawatra was ordered to step down on Wednesday over the illegal transfer of her security chief. Another court has indicted her for negligence.
A caretaker government led by Thaksin Shianwatra loyalist Niwattumrong Boonsongpaisan is running the country and says it is working towards a July 20 election.
The opposition says it will not contest the polls and that political reforms must be introduced first.
On Friday, a rally of “yellow shirts” ended with police firing tear gas and water cannon. At least five demonstrators were injured.
At least 25 people have died over the course of the protests in Thailand.