Some 45.2 million people are eligible to vote in the poll, which Thaksin called three years early in a bid to end weeks of mass street rallies set off by allegations that he abused his office for personal gain.

Polling stations are due to open at 8:00 am (0100 GMT) and counting will start after the polls close seven hours later. Provisional results are expected to trickle in throughout Sunday night.

While the result may seem a foregone conclusion -- Thaksin's Thai Rak Thai (Thais Love Thais) party is running unopposed in 200 of 400 constituencies -- the election is unlikely to resolve the political standoff.

Election officials warn that even an apparent victory might not be enough to form a parliament. Dozens of the party's candidates could fail to win the 20 percent of votes required to take office.

Some 322 of 941 candidates have already been disqualified, meaning there might not be enough lawmakers elected to confirm a new prime minister, forcing by-elections and leaving the country facing months of political limbo.

The Election Commission late Saturday said 589 candidates would contest the poll, while the Supreme Court was still deciding on a further 30 candidates.

The self-made billionaire, 56, remains hugely popular in rural areas, where 60 percent of Thailand's 63 million people live. Elections in February 2005 saw him returned to office with 377 of parliament's 500 seats held by his party.

But his autocratic style has angered many in the urban middle class.

But protesters, angry over a controversial stock sale that saw Thaksin's family make 1.9 billion dollars tax free, have vowed to continue demonstrations calling for him to quit long after the ballots have been counted.

Ahead of a 6:00 pm (1100 GMT) end to campaigning Saturday, Thaksin again urged his opponents to abide by the election results, saying: "Whatever the people's decision is ... every political party, group and organisation must respect it."

He said that after the election he would consider "every demand" of his opponents, including calls that he quit.

In the absence of opposition candidates, the biggest challenge to Thaksin in Sunday's election is the "no vote" option that could be exercised in Bangkok and the troubled south, where anger towards the premier is most fierce.

Thaksin has pledged not to take office if he wins less than 50 percent of the vote, and his critics have called for voters to tick the abstention box on the ballot in a show of no confidence, saying this could deny Thaksin his majority win.

Sirirat Choonhaklai, an associate professor in public administration at Bangkok's Mahidol University, downplayed the impact of the "no vote" option, saying Thaksin's support remained strong in the country's north and centre.

Another analyst said Thaksin's opponents would most likely just stay away from the polls.

"It takes a lot to go out and vote for no one," said Thitinan Pongsudhirak, professor of political science at Chulalongkorn University in Bangkok.

According to Sirirat, a landslide would be the best way to end the political crisis, as a marginal victory would further fuel anti-Thaksin protests.

"If (Thaksin) gets a landslide victory, people won't be able to say he can't rule the country," Sirirat told AFP. "If he doesn't get ... a comfortable victory, those people will have an excuse to come out and protest again."

The People's Alliance for Democracy, which has been holding rallies in Bangkok since late February to demand Thaksin quit, suspended its protests Thursday but vowed to resume them April 7.

Around 100,000 people rallied in Bangkok last weekend in the biggest in a series of demonstrations calling for him to quit, urging the king to intervene and appoint a new prime minister.

The opposition Democrat party has rejected Thaksin's offer to form a government coalition if he wins, insisting on constitutional reforms to limit the powers of the prime minister.

The premier has said he would consider constitutional reforms overseen by a neutral body.