Thai voters go to the polls Sunday to choose a new parliament. Here are some key facts about the election:

The Main Candidates:

Prime Minister Abhisit Vejjajiva:

The Oxford educated Mr. Abhisit enjoys strong backing from the Thai military and the country's royalist elite. He was appointed prime minister in 2008, following two years of political upheaval triggered by a 2006 military coup that toppled then-Prime Minister Thaksin Shinawatra. Controversial court rulings later disbanded two pro-Thaksin ruling parties accused of electoral fraud, clearing the way for the rise to power of Mr. Abhisit and his Democrat Party.

The Abhisit government faced weeks of major street protests from Thaksin supporters in 2010. Tens-of-thousands of protesters at the so-called “Red Shirt” rallies tried to force Mr. Abhisit and his government from power by occupying Bangkok's main business district. When the military intervened to end the protests, more than 90 people were killed and hundreds of other were injured.

Yingluck Shinawatra:

Yingluck is the younger sister of deposed Prime Minister Thaksin, who faces a two-year prison term at home and currently lives in exile in Dubai. As head of the populist opposition Puea Thai party, the 44-year-old businesswoman — like her exiled brother — enjoys broad support by Thailand's rural and urban lower classes, as well as some “new money” business people.

Critics say Yingluck will be used as a front by her brother, who has said he would like to return to his homeland if his sister Yingluck wins and he is granted an amnesty. Mr. Thaksin told Australian radio in May that he has no ambition to return to political power. However, he said he continues to advise the Puea Thai party and says he taught and trained his sister in politics.

Polls show Yingluck is likely to win the most seats in the 500-seat parliament. But analysts say her party is likely to fall just short of a majority — an outcome that could lead to post-election instability and raise the possibility of further military intervention.

Others:

A total of 29 parties are contesting the election — Thailand's 26th since ending seven centuries of absolute monarchy and becoming a democracy in 1932. Policy debates range from minimum wage issues, inflation, unemployment, education initiatives and health care, to refugee concerns along the Burmese border and tensions with Cambodia over land disputes near that border. However, those issues and others remain largely overshadowed by the broad and simmering class divide separating the country's ruling elites from the populist-leaning opposition.

The Parliament

Voters will fill 375 seats in the 500-seat parliament, with lawmakers serving four-year terms. The remaining 125 seats will be filled by the parties, based on the percentage of votes each party wins.

The Electorate

There are about 47 million voters in the country of 67 million residents, and voter turnout in recent polls has been high. Nearly 75 percent of the electorate voted in 2007 polls.

The Military

Thailand's military has a long history of interfering in politics, having mounted 18 coups or attempted coups since 1932, and its powerful army chief, General Prayuth Chan-ocha, recently urged the Thai public to elect “good people.”

In comments June 15, the general said security services had found growing evidence of disrespect for the country's revered monarchy. However, he said the military would remain neutral in the polls.