Groups of protesters supporting Move Forward Party (MFP) leader Pita Limjaroenrat as the nation's 30th prime minister have sprung up across Bangkok this week.
They began after parliament rejected Mr Pita's second bid for the premiership and the Constitutional Court's decision to suspend him as a member of parliament.
The United Front of Thammasat and Demonstration, the Talugas Group and the Student Organisation of Thailand announced on their Facebook pages their plan to hold rallies on Friday and on Sunday.
Friday's gathering will begin outside Kasetsart University's auditorium at 5pm and then again at 7pm outside the Bangkok Art & Culture Centre.
The People Assembly Reforming Thailand and its allies on Thursday kicked off an 11-day campaign in support of a "democratic government" starting at the Pathumwan intersection.
Sombat Boonngam-anong, a political activist, posted on his Facebook page a call for another gathering on Sunday at the Asok intersection from 5pm to support Mr Pita and the MFP.
The People Movement for a Just Society (P-move) also issued a statement condemning what it described as attempts to destroy democracy and block a consensus reached by 14 million voters in the May 14 general election for the MFP to lead a new government.
The organisation also called on senators to resign en masse and for all pro-democracy movements to come out to demonstrate their opposition against "distorted democracy".
