He told protesters on stage at his Pathumwan rally site that PDRC members from all of Bangkok's rallies will be out to urge the public to continue pressing the caretaker government to resign and demanding a national reform before the election.
The government has insisted that the snap poll must be held on Sunday and ordered the Election Commission (EC) to organise the nationwide polls accordingly.
If the caretaker prime minister and her Cabinet refuse to resign, a massive show of force will be inevitable and the entire capital will be paralysed on Sunday, said the PDRC secretary general.
He said Thai people should not worry about losing their future voting rights if they do not cast their ballots on Sunday.
The law imposes that a general election must be held simultaneously in a single day but it is evident that balloting will be impossible in several areas especially the South, the North and central region including Bangkok, he said.
He predicted that the election will be declared invalid - similar to the incident in 2005.
Thaworn Senneam, a PDRC leader, said the anti-government movement's members agreed to boycott the election though they would lose their political rights to run in future elections.
Polling boxes and ballots have yet to be delivered to various southern constituencies which have been blockaded by protesters, he said.
He said the PDRC will not disrupt the election but demonstrators will organise a major rally in Bangkok on Sunday.
Mr Thaworn will lead about 500 protesters from the Victory Monument this morning to join Mr Suthep's group at On-nut station of BTS Skytrain to start the march along Sukhumvit Road to Asoke intersection.
He said two PDRC lawyers will today petition the Senate's anti-corruption sub-committee against the caretaker government for failing to investigate 23 cases of attacks and violence during the three-month protests which killed five people and injured more than 300 others.
Mr Thaworn said the Civil Court is scheduled to announce its ruling today on his complaint, asking the government to revoke the Emergency Decree.
"Whatever the court decides, I'll respect the verdict," he said.