The protests led by the People's Democratic Reform Committee (PDRC) on Monday are intended to wrap up the one-month of demonstrations which began at Samsen railway station before moving to three key areas - Democracy Monument, the Finance Ministry compound and the Government Complex.
PDRC spokesman Akanat Prompan announced on Sunday that they will not intrude on the compound of the Prime Minister's Office. However, the demonstrators will surround it.
Mr Akanat was confident that the anti-government campaign on Monday will be a historic event leading to a major change other than a House dissolution or Prime Minister's Yingluck Shinawatra's resignation. The turnout of people on Monday would be a key factor to send the message to the prime minister to show her responsibility, he added.
Of the 50 or more groups, nine would be directed by the PDRC - two from the Thonburi side of the Chao Phraya River and seven from the Bangkok side. All columns, except the one led by PDRC leader Suthep Thaugsuban, would start to move at 9.39am. The main rally led by Mr Suthep will take off from the Chaeng Wattana government offices complex at 8.29am.
Apart from the protesters directed by the PDRC, the others to join the rally include the State Enterprises Workers Relations Confederation and business groups. They will march on different routes to the same destination.
Sathit Wongnongtoey, a core member of the PDRC, said the groups would include labour unions of the Electricity Generating Authority of Thailand and Thai Airways International, Silom and Yaowarat business groups, and students and faculty members of Thammasat, Mahidol, Chulalongkorn, Kasetsart, National Institution of Development Administration, Ramkhamhaeng, Srinakarinwirot and Silpakorn universities.
Former leader of the People's Alliance for Democracy Sondhi Limthongkul will join the rallies for the first time by leading a march from Ban Phra Arthit after he returns from an overseas trip on Monday morning, an aide close to him said.
Pheu Thai Party spokesman Prompong Nopparit said the government could control the situation and challenged Mr Suthep to honour his promise by turning in to police if the rallies fail as he is under an arrest warrant on serious charges including instigating unrest.