The count in the House of Representatives was unofficial and the chamber needed to official endorse the results before Abhisit could be declared prime minister. The chamber normally has 480 members, but because of vacancies currently numbers 437. One MP died on the eve of the voting.
The lower house vote followed months of instability caused by anti-government demonstrations that culminated late last month with a weeklong takeover of Bangkok's two airports.
The airport siege ended after a court ruling on Dec. 2 dissolved the ruling People's Power Party and two coalition partners and handed a five-year political ban to former premier Somchai Wongsawat, who is Thaksin's brother-in-law. The remnants of the PPP regrouped as the Phuea Thai Party, which are also seeking a majority in Monday's session.
The anti-Thaksin protest movement seeks to purge politics of the influence of Thaksin - who was ousted by a 2006 coup after being accused of corruption and abuse of power - and has threatened new but unspecified activities if Parliament elects a leader with links to him.
"The Democrats are positioned to win this round. They seem to have the votes, the support of the private sector and the business community which hopes for temporary respite," said Sukhum Nuansakul, a political scientist at Bangkok's Ramkhamhaeng University, shortly before the vote began.
"But the peace is likely to be short-lived. The fundamental problem has not been resolved," Sukhum said. "A Democrat win sets the stage for another round of street protests, this time by pro-Thaksin groups."
About 1,200 police were deployed outside Parliament for the session Monday amid concerns about a street protest, said Bangkok police chief Lt. Gen. Suchart Maunkaew.
Thaksin now lives in exile, having fled Thailand ahead of an October conviction on a conflict of interest charge.
But he continues to play an active role in politics, and Saturday night Thaksin gave a prerecorded video speech to a rally of more than 40,000 of his supporters who gathered at a stadium in central Bangkok.
Thaksin decried inappropriate interference in the political process - a reference to the army's alleged intervention in favor of the Democrats - and denounced lawmakers who had been loyal to him but switched their allegiances. The army traditionally wields a great deal of influence in Thai politics.
The speech had been ballyhooed in advance as a last-ditch effort to rally support ahead of the parliamentary session but it had no evident effect on the political balance.
Thaksin, a former telecommunications magnate, is still supported by many in Thailand's impoverished countryside because of his populist policies during his six years in power.
Democrat leader Abhisit told reporters Sunday that it was his party's "responsibility to offer another choice for the country when the former government has failed." He said his party would focus on national harmony and economic issues.
Thailand's economy has taken a battering due to the global slowdown, a local climate of uncertainty and the seven-day stoppage of international flights that battered the country's essential tourism industry and stranded upward of 300,000 travelers. Some economists are predicting Southeast Asia's second-biggest economy will slip into recession next year.
Suthep Thuagsuban, the secretary-general of the Democrat Party, said he was certain his party would get about 260 votes in Parliament on Monday.
"Thaksin's maneuvering could not sway the lawmakers from voting for Abhisit," Suthep said. "We are confident people want a new beginning."
But acting Public Health Minister Chalerm Yoobamrung, a Thaksin loyalist, said the Phuea Thai Party has the support of at least 230 lawmakers who will vote for Pracha, who heads the small Puea Pandin party.
As former police chief, Pracha was known as "The Eagle of the Northeast" for his reputation as a crime fighter in the rural region which is also Thaksin's stronghold.
