BANGKOK - Tens of thousands of Thai opposition protesters marched through Bangkok Saturday calling for the resignation of Prime Minister Yingluck Shinawatra, who faces a possible ban from politics for alleged negligence.
The new show of strength by the anti-government movement came on the eve of elections for the upper house of parliament, whose members could decide Yingluck's fate.
"I have come out to preserve democracy," said protester Jirapa Tantingarmkasem, who joined the march from the rally base in Lumpini Park to the city's Royal Plaza.
"I ask everyone to come out to protest. Fight! Fight!"
Hundreds of demonstrators also swarmed into the grounds of the government headquarters, which have not been used by Yingluck's cabinet for months because of protests targeting state buildings.
Yingluck has withstood five months of street rallies seeking to force her from office and end the political dominance of her billionaire family.
Thailand is bitterly divided between opponents and supporters of her elder brother, the fugitive former premier Thaksin Shinawatra.
The billionaire tycoon-turned-politician was toppled in a coup in 2006 after clashing with the royalist establishment. He fled Thailand in 2008 to avoid jail for a corruption conviction and lives in Dubai.
Political violence, often targeting protesters, has left 23 people dead and hundreds wounded in grenade attacks and shootings in recent months, although the bloodshed has abated since the rallies were scaled back at the start of March.
The kingdom is in legislative limbo with only a caretaker government following incomplete February elections since nullified by the Constitutional Court.
The opposition movement wants to install a temporary unelected government to oversee electoral and anti-corruption reforms before new polls are held.
"We will show our power to the government - people will not accept elections without immediate reforms first," firebrand rally leader Suthep Thaugsuban told supporters Saturday.
Yingluck has been summoned to appear before the National Anti-Corruption Commission (NACC) by Monday to defend herself against negligence charges linked to a rice subsidy scheme.
If indicted by the NACC - which says she ignored warnings of corruption and financial losses in the flagship policy - she would face an impeachment vote in the upper house that could result in her removal from office.
The charges have injected extra rivalry into senate elections due to be held on Sunday for about half of the seats in the upper house.
The remaining, unelected senators are appointed by institutions seen as allied to the anti-Thaksin establishment.
Thaksin's supporters, the "Red Shirts", have warned they will not accept the removal of another democratically elected government.
Their street rallies against the previous government in 2010 resulted in street clashes and a military crackdown that left dozens dead.