Sixty-five groups allied with the anti-government People's Democratic Reform Committee (PDRC) will join a procession from Lumpini Park to the Royal Plaza on Saturday to push for national reform before elections.
Demonstrators will converge at Lumpini Park, the PDRC's main protest site, at 7am today, before setting off.
Caretaker Labour Minister and Centre for the Administration of Peace and Order director Chalerm Yubamrung yesterday estimated that no more than 30,000 people would join the PDRC rally today.
He said Bangkokians were fed up with attempts to bring in an interim prime minister.
The march is to be divided into six processions made up of the network of medical volunteers, students from Kasetsart, Khon Kaen, Chiang Ma and Thai Chamber of Commerce universities, a group of blind people and PDRC networks from various provinces.
The first procession will begin in front of the Rama VI monument, the second at Lumpini Park's Gate 3 opposite the U-Chu Liang Building, and the third will set off in front of the park near Witthayu intersection.
Lumpini police station is the venue for the fourth. The fifth procession will converge at Witthayu and Sarasin intersection and the sixth will start in front of the park's Gate 7.
Sathit Wongnongtoey, a leading PDRC member, said PDRC supporters in Thon Buri will meet at the Taksin bridge on Phra Nakhon side at 7am. They will set off for Lumpini Park at 8am.
PDRC co-leader Nattapol Teepsuwan said PDRC demonstrators will march from the Lumpini rally site to the Royal Plaza along Ratchadamri Road before they head towards the Royal Plaza via Si Ayutthaya Road.
PDRC secretary-general Suthep Thaugsuban said the PDRC-led march was aimed at showing that the people, who are the ''real owners'' of the country, want national reform to be implemented before a general election.
''In summary, the march aims to make our intention known that we want immediate national reform, not [a rushed] election. We want to say this; 'Don't hold the election [too soon]. Masses of people [will] definitely boycott it,'' said Mr Suthep.
Apart from the rally in Bangkok, similar protest marches will also be held in other provinces.