Anti-government protesters rally in Bangkok on day before Senate vote

Tens of thousands of Thai anti-government protesters rallied across Bangkok on Saturday in their latest bid to topple Prime Minister Yingluck Shinawatra, a day before a crucial vote to elect a new Senate.

Waving flags and blowing whistles, protesters marched from Lumpini Park in the business district of Bangkok toward the city’s old quarter. Protesters retreated to Lumpini Park earlier this month after a brief hiatus in anti-government rallies.

"The rally has been largely peaceful and very disciplined. Protesters are now heading back to their base in the park after a series of symbolic ceremonies," Paradorn Pattanathabutr, a security adviser to the prime minister, told Reuters, adding that the crowd was expected to reach about 30,000 people.

A grenade exploded as protesters passed the Foreign Ministry offices, but no one was hurt, police said. It was unclear who was responsible for the attack.

Yingluck's opponents have tried a variety of tactics for the past four months to force her out of office. They have blocked Bangkok's major intersections, stormed government offices and most recently transformed the city's sprawling Lumpini Park into a protest headquarters overrun with tents and sleeping bags.

Thailand has been in crisis since former premier Thaksin Shinawatra, Yingluck's brother, was ousted in a 2006 coup. The conflict broadly pits the Bangkok-based middle class and royalist establishment against the mostly poorer, rural supporters of the Shinawatras.

Saturday's march is seen as a test of the anti-government movement's popularity as the number of protesters has dwindled considerably in recent weeks.

By mid-afternoon police put the crowd at around 20,000. Around 500 protesters from the Network of Students and People for the Reform of Thailand, a splinter group of the main protest group, broke into the compound of Government House. Though the building used to house the prime minister, it has largely been abandoned by officials after being occupied by protesters in November -- when Yingluck was temporarily forced into hiding.

Over the past five months, protesters have shut state offices and disrupted a Feb. 2 election by blockading polling stations across the country. The election was nullified by a court on March 21, leaving Thailand in political limbo and Yingluck at the head of a caretaker government with limited powers.

Election officials have said it will take at least three months to organize a new election.

Since the current round of protests kicked off in November, 23 people have been killed in sporadic political violence and hundreds of others injured.

Protesters want political and electoral reforms before a new general election and to rid the country of Thaksin's influence.

"We will no longer accept this oppressive regime. They, Thaksin and Yingluck, are no longer welcome in Thailand," protest leader Suthep Thaugsuban told reporters as he led protesters who shouted, "Yingluck, get out!"

On Monday, Yingluck is due to submit her defense to the National Anti-Corruption Commission in a case her supporters call politically motivated. Criticisms of the so-called rice subsidy scheme could lead to the prime minister's impeachment.

The rice subsidy program — a flagship policy of Yingluck's administration that helped win the votes of millions of farmers — has accumulated losses of at least $4.4 billion and has been dogged by corruption allegations. Payments to farmers have been delayed by many months.

If the commission decides to indict Yingluck and forward the case to the Senate for an impeachment vote, government supporters have vowed to rise up in her defense.

The current Senate is pro-Thaksin, but that could change in Sunday's election, which will fill 77 seats in the 150-seat Senate. The remaining seats are appointed, and a government attempt to make the Senate a fully elected body was one of the triggers for the unrest that started in November.

Yingluck's Red Shirt supporters have vowed to stage their own mass rally next Saturday, though they have not yet said whether it will be held in the capital, which many fear could lead to clashes between the two sides.

Wire services