The supporters of ousted premier Thaksin Shinawatra began snaking across the capital mid-morning, dressed in their distinctive red and bringing traffic in some areas to a halt.
Police estimated there were around 25,000 demonstrators, who waved, cheered, honked horns and blared music in their day-long drive to recruit the urban middle classes and revive their waning rally, now in its seventh day.
In what they have increasingly dubbed a class war, the so-called Red Shirts say they are fighting Thailand’s elite in bureaucratic, military and royal circles, whom they accuse of ousting elected governments.
The mainly poor, rural protesters say prime minister Abhisit Vejjajiva’s government is illegitimate, as it came to power with army backing via a December 2008 parliamentary vote after a controversial court ruling removed Mr Shinawatra’s allies.
“We will travel to find love from the people of Bangkok and to unite them with us, the poor peasants, to overthrow the elite-backed government,” Red Shirt leader Veera Musikapong told the crowds before their convoy set off.
Mr Vejjajiva, who has stood firm against the protesters’ demand for snap elections, criticised the depiction of a class struggle.
He said Mr Shinawatra, who was ousted in a coup in 2006, was an “obstacle to negotiation” between the government and Red Shirts, who have rejected the prime minister’s conditional offer of talks.
Despite the buoyant mood of Saturday’s convoy, numbers were far down on their peak of more than 100,000 when the rally began last weekend.
The Thai government later announced that one of its ministers would meet a representative of the Red Shirts on Monday.
Satit Wonghnongtaey, the minister attached to the prime minister’s office, will meet Weng Tojirakarn, considered a second-tier leader of the protest movement.