By Amy Sawitta Lefevre
BANGKOK (Reuters) - Thailand's main opposition party won an election for the governor of Bangkok on Sunday, dealing a surprise blow to the ruling party of exiled former Prime Minister Thaksin Shinawatra which had hoped to win the city and cement its supremacy.
Incumbent governor and Democrat Party member Sukhumbhand Paribatra beat the candidate of Thaksin's Puea Thai Party, winning almost half the vote, the city administration said as the count neared completion.
"The Democrats won because a large part of Bangkok were scared of Puea Thai holding too much power," political analyst Kan Yuenyong at Siam Intelligence Unit, told Reuters.
"In the long-term, Thailand is heading towards a system ruled by two main political parties."
Opinion polls had suggested Puea Thai candidate Pongsapat Pongcharoen, a former policeman, would drive the middle-class establishment party, the Democrats, out of power in Bangkok and usher in his party which is favored by the poor.
Polls had shown Puea Thai leading by up to a nearly 17 percent margin.
It was the fourth consecutive Bangkok election victory for the Democrats, Thailand's oldest political party, which enjoys support from the middle class and conservative elite.
Puea Thai and its former incarnation, the Thai Rak Thai, have never won in Bangkok but is hugely popular with voters in poor north and northeast regions, who handed the party a victory in the last general election in 2011.
Thaksin, a graft-convicted telecoms tycoon, remains a powerful and popular political force from his home in self-exile in Dubai.
His sister is Prime Minister Yingluck Shinawatra who has presided over a period of calm since winning the 2011 election after years of upheaval that began with the ousting of Thaksin by the military in 2006.
Sukhumbhand Paribatra, a member of the royal family and a former deputy foreign minister, thanked Yingluck for promising close cooperation with his city administration.
The two were criticized for failing to work constructively during serious floods in the city two years ago.
Home to more than 9 million people, Bangkok faces numerous problems including traffic chaos, pollution and crime.
(Editing by Robert Birsel)