With more than 70 percent of the vote counted in all but two Bangkok districts, abstentions outnumbered votes for Thai Rak Thai in 27 of the capital's 36 constituencies, The Nation newspaper reported on its Web site, citing the Election Commission. In elections last year, Thaksin's party swept the capital.

Somchai Srisutthiyakorn, of the election watchdog People's Network for Election, estimated that up to 40 percent of votes cast Sunday were abstentions, compared with about 1 percent in last year's election.

The "Vote for No Vote" campaign also appeared to have strong support in southern Thailand, which historically favors the main opposition Democrat Party.

Early returns showed Thaksin was clearly popular in the north ¡ª his home area ¡ª and the northeast, where Thailand's rural majority has benefited from his administration's generous social welfare and economic assistance programs.

Because of the boycott, Thai Rak Thai could be the only party to hold seats in the new legislature. Candidates from obscure parties with no lawmakers in Parliament ran in the remaining constituencies, and there was no indication that any had enough votes to claim a seat.

However, political analysts predict that some ruling party candidates, particularly in Bangkok and the south, will not be able to take office because of minimum vote requirement laws.

Election law stipulates that uncontested candidates must win the support of at least 20 percent of registered voters ¡ª highly unlikely in some districts. Any seats left unfilled could lead to several more rounds of voting in those districts before a prime minister can be chosen.

The opposition hoped the boycott would make it impossible to fill all 500 seats, which many legal experts say could lead to a failure to convene Parliament and form a new government.

Abhisit Vejjajiva, head of the Democrat Party, said the strong abstention vote showed that Thaksin does not have a true mandate.

"There are a lot of people who voted 'No Vote' this time," Abhisit said. "It shows that most people think this election is not the answer to the problem right now. And that's the reason the Democrat Party didn't join the election in the first place."