The latest protest in two months of political turmoil followed a Bangkok sit-in overnight that drew around 50,000 people onto the streets calling on Prime Minister Thaksin Shinawatra to step down before Sunday's vote.

"This is a very critical moment. Only people power can force Prime Minister Thaksin to quit," rally leader Chamlong Srimuang told the crowd, which waved banners calling the commission members "political criminals."

Thousands of Thai protesters who spent the night in a downtown Bangkok street to demand the prime minister quit cut short their demonstration yesterday, just three days before troubled elections.

Support for Chamlong's movement appeared to be waning. He cut short the sit-in at a major Bangkok retail district, which was originally planned to run until Friday, after widespread complaints over traffic jams.