The Pheu Thai-led alliance's hope of forming a coalition government look dashed after the Election Commission (EC) endorsed 149 party-list MPs on Wednesday, which effectively reduced the number of seats garnered by the alliance to 245.

After the poll agency decided to award one party-list seat to 12 small parties, the Palang Pracharath Party (PPRP) is now moving at full speed to form a rival coalition, and key factions within the party have already begun to discuss the allocation of cabinet seats among its members, said a PPRP source.

The source said that the Bhumjaithai and Democrat parties will be given six seats each in the cabinet, while the Chartthaipattana Party will get two seats.

"Meanwhile, smaller parties are joining forces to negotiate for more seats," added the source.

Meanwhile, the Pheu Thai Party and its core ally, the Future Forward Party (FFP), are prepared to challenge the election results which were announced several hours after the Constitutional Court ruled unanimously in the morning that Section 128 of the organic law on elections of MPs is constitutional.

Shortly after initial results of the March 24 vote were made available, the alliance held a press conference to announce it had secured 255 seats, which is comprised of 137 MPs from Pheu Thai, 88 from the FFP, 12 from Seri Ruam Thai, seven from the New Economics Party, seven from Prachachat, five from Puea Chat and one from the Thai People Power Party.

However, based on the official election results, the group's total seats shrank to 245. The FFP saw its party-list seats reduced to 80, the New Economics Party received only six seats, the Seri Ruam Thai received just 10 seats, and one Pheu Thai winning candidate was disqualified.

FFP secretry-general Piyabutr Saengkanokkul said a political party receiving fewer than 71,000 votes, which is the minimum threshold for a seat in the House, is not eligible to receive a party-list seat. He stressed that only 15 political parties are eligible to be awarded party-list seats, because the Pheu Thai Party already won a large chunk of constituency seats.

The Pheu Thai Party on Wednesday accused the EC of "deliberately using its power against the charter and the law" and vowed to take legal action against the EC. Khunying Sudarat Keyuraphan, Pheu Thai's chief strategist, said the EC owes an explanation to parties that lost their party-list seats as a result of its calculation method, and suggested the court stopped short of endorsing the EC's calculation.