Opinion polls point to a win by the opposition Puea Thai (For Thais) party led by Yingluck Shinawatra, sister of ousted premier Thaksin Shinawatra, over the Democrat Party of Prime Minister Abhisit Vejjajiva.

Thaksin, who lives in self-appointed exile in Dubai after being ousted by the military in 2006, looms large over the election, popular with the red shirts supporters of Puea Thai and hated by the Democrat elite who want him to stand trial for corruption.

The risk of turbulence lies in the margin of a Puea Thai win and the reaction of the red shirts, mostly rural and urban poor whose protests last year prompted a bloody crackdown. Key as well will be the response of the military, which has a history of intervening in Thai politics.

Election days in Thailand are traditionally dry affairs, with alcohol sales banned from 6 pm on July 2 to midnight on July 3 and the go-go bars closed.