Thais voted on Wednesday for a new Senate in an election marred by violence in the restive Muslim south and allegations of vote buying.
The poll could intensify a campaign against Prime Minister Thaksin Shinawatra if his supporters come to dominate the supposedly neutral upper house, meant to act as a check on the government and select members of independent watchdog bodies.
Despite a ban on party affiliation, many of those vying for the 200 seats are related to members of the government, and anti-Thaksin campaign leaders say the election can only produce a more partisan body that will bring his foes back on to the roads.
More than 44 million of Thailand's 63 million people are eligible to choose from among 1,500 candidates vying for a single six-year term in the Senate. Polls closed at 3 pm (0800 GMT) and results will trickle out on Thursday.
The Bangkok-based democracy watchdog, the People's Network for Elections (P-Net), said turnout would fall short of the 70 percent target set by the Election Commission, and vote buying was reported across the country, including Bangkok.
P-Net said at least 100 million baht ($2.6 million) was spent by some candidates in the impoverished north-eastern province of Sisaket alone, where seven candidates are racing for one seat.
SOUTHERN UNREST: Violence marred voting in the predominantly Muslim south where suspected separatist militants killed two policemen and wounded 17 officers and civil servants in two bomb attacks and a gun ambush in the province of Narathiwat, police said.
More than 1,100 people have been killed in a two-year separatist insurgency in the Malay-speaking region.
Among the candidates this time, about 50 are relatives or spouses of Thai Rak Thai politicians and 20 are relatives of senators who have served their term, the independent Matichon daily said on Monday.