BANGKOK, Thailand (AP) - Thailand’s main opposition party said it plans to form a new government with the help of defectors from the ruling coalition, a move certain to appease an anti-government group that recently paralyzed the capital, shutting down its main international airport for a week.

The opposition Democrat Party announced Saturday it had mustered the backing of 260 lawmakers in the 400-seat lower house, allowing it to form a government with Oxford-educated party leader Abhisit Vejjajiva as the new prime minister.

But the party’s apparent triumph, managed during a still chaotic situation the day after Bangkok’s Suvarnabhumi airport reopened, will not be sealed until Parliament meets within the next 30 days to endorse Abhisit and the five-party coalition behind him. The former ruling party said it would not give up the fight.

The Democrat party is supported by the People’s Alliance for Democracy, an activist group that headed mass demonstrations against several recent governments led by exiled former Prime Minister Thaksin Shinawatra and his allies. The protests culminated in a weeklong siege of the capital’s two airports.

The Democrats cobbled their coalition together against a somber backdrop: Thailand’s revered 81-year-old King Bhumibol Adulyadej, regarded as a cornerstone of stability, is ill, and it was feared that if the ruling coalition had selected a new prime minister close to Thaksin, that could again ignite mass protests.

But for now it appears the opposition has the upper hand. Democrat Party Secretary-General Suthep Thaugsuban told reporters that negotiations with the other parties had been "the smoothest discussion" he has ever had because everyone realized the countrystability was at stake.

"This was the hardest decision we have made, but the country needs to move forward. We have to think of the country’s survival and so we apologize to our MP friends and the people who support us, but we can’t work with them anymore," said Boonjong Wongtrairat, a representative of a faction of 37 MPs who defected from the government camp and its leading Phuea Thai Party.

"Things are not final yet. Right now, it’s a fight between the anti-democracy group and pro-democracy group. The situation is quite clear and we can’t accept this," said Phuea Thai Party member Worawat Ua-apinyakul.

The Democrats were expected to face problems if they form a new government amid Thailand’s polarized political arena.

Sombat Chanthonwong, a political science professor at Bangkok’s Thammasat University, said many would find it difficult to accept Abhisit as the new prime minister because he did not emerge from an electoral contest.

"How can we have a prime minister who doesn’t come from a democratic process? I don’t get it," he said.

British-born Abhisit, 44, is an articulate, sophisticated politician but critics say he is out of touch with ordinary people, particularly the rural majority, and lacks charisma. His party’s suppor$ers include Bangkok’s middle class, influential military figures and foreign investors who see him as a stabilizing force.

Thaksin is still popular among the rural masses, reflecting the deep divide between the urban elite and the country’s poor.

The political developments came as the country’s main international airport was being restored, although an airport public relations official said Saturday it could be at least a month before traffic was back to normal. The official spoke on condition of anonymity because she was not authorized to speak to the media.

Suvarnabhumi international airport reopened Friday following a siege that trapped more than 300,000 travelers and dealt a heavy blow to Thailand’s tourism-dependent economy.

The government was dissolved by a court order Tuesday for election fraud. A number of members of ousted Prime Minister Somchai Wongsawat’s People Power Party regrouped in a new party, Pheua Thai, and retained the right to name a new prime minister.