Pheu Thai, the largest party in Thailand's caretaker government, will meet today to choose a successor to ousted former Prime Minister Srettha Thavisin, in an effort to consolidate its coalition a day before a crucial parliamentary vote on a new prime minister.

The party must choose one of two qualified candidates, including former Justice Minister Chaikasem Nitisiri (76 years old) and party leader Paetongtarn Shinawatra (38 years old), daughter of former Prime Minister Thaksin Shinawatra.

The Bangkok Post quoted a source in the Pheu Thai party as saying that Mr. Chaikasem did not appear to be in good health, while Ms. Paetongtarn's future depended on the family's decision and she was expected to face heavy political pressure.

Another source said Mr Chaikasem would be nominated, as Ms Paetongtarn had declined to run.

Mr. Srettha is the fourth prime minister of this party to be removed by the court.

The Pheu Thai party moved quickly to defend its advantage, with media broadcasting live footage late on August 14 of coalition partners visiting the residence of Mr Thaksin, the party's founder and influential figure.

“They want to be decisive. The longer it takes, the more arguments and power struggles will happen, so the faster the better,” said political scientist Thitinan Pongsudhirak at Chulalongkorn University.

"If they can vote earlier, the vote will be more manageable. They can control the outcome of the House of Representatives," the expert said.

The House of Representatives is expected to convene on August 16, a swift move compared to last year when the House of Representatives waited two months to vote on a prime minister after the election.

The 11-party coalition, which holds 314 seats in the lower house, is expected to have no trouble electing a prime minister on August 16, if the coalition remains intact. To become prime minister, a candidate needs the approval of more than half of the current 493 lawmakers.