The Pheu Thai Party has now sealed a deal with the Palang Pracharath Party (PPRP) and United Thai Nation (UTN) Party in which the two parties have agreed to vote for Pheu Thai's prime ministerial candidate in exchange for slices of the cabinet quota cake, according to a source.
An official announcement will follow, but with the two parties agreeing to join the coalition, the Pheu Thai-led coalition now boasts 315 MPs, said the source.
Pheu Thai has 141 MPs while Bhumjaithai has 71 MPs, the PPRP 40, the UTN 36, Chartthaipattana 10, Prachachat nine, Pheu Thai Ruam Palang 2, Chartpattanakla 2, with Seri Ruam Thai Party, Plung Sungkom Mai, Thongthee Thai and the New Democracy Party all having one MP apiece.
Pheu Thai has agreed that one cabinet position will be allotted for nine MPs each has, said the same source.
The deal would see Pheu Thai's Srettha Thavisin appointed prime minister, while party leader, Cholnan Srikaew, would serve as both deputy prime minister and education minister, said the source.
Pheu Thai deputy leader Phumtham Wechayachai would become the interior minister, and party secretary-general Prasert Chantararuangthong would get the transport ministry role, said the source.
Pheu Thai list-MP for Chiang Mai Julapun Amornvivat would take the energy portfolio while Panpree Phathithanukorn and Puangpet Chunlaiad, both key party figures, would become the foreign minister and a PM's Office minister, respectively, said the source.
Somsak Thepsutin, a Pheu Thai list-MP, will likely become the new agriculture and cooperatives minister, while list-MP Suriya Jungrungreangkit is negotiating for a transport ministry position, said the source.
As for the positions of finance and defence minister, Pheu Thai is approaching two outsiders who are highly qualified to hold these posts, said the source.
The Bhumjaithai Party would be awarded four cabinet positions in the Ministry of Transport, Ministry of Agriculture and Cooperatives, Ministry of Commerce and Ministry of Tourism and Sports, said the source.
In the cabinet quota for the PPRP, Pol Gen Patcharawat Wongsuwon, the party's chief adviser, would become a deputy prime minister and the natural resources and environment minister, said the source.
PPRP secretary-general Capt Thamanat Prompow is said to have a good chance to become the agriculture and cooperatives minister, while PPRP MP for Kamphaeng Phet Pai Leeke may get the nod as deputy interior minister.
The UTN is interested in the energy ministry and also the digital economy and society ministry, said the source.
Prachachat has nominated Pol Lt Col Tawee Sodsong, a list-MP, as the new justice minister, while the Chartthaipattana leader, Varawut Silpa-archa, will likely become the new tourism and sports minister, said the source.
Despite insisting Pheu Thai had yet to reach any formal agreement with the PPRP and the UTN, Mr Phumtham has admitted that Pheu Thai is left with no other choice but to include them for the sake of stability.
In its campaign, Pheu Thai said it would not work with either because it was UTN prime ministerial candidate Gen Prayut Chan-o-cha who staged the 2014 coup, while PPRP leader Gen Prawit Wongsuwon has close ties with the coup-makers.
"I expect the government to take office no later than October," he said.
Meanwhile, Move Forward Party (MFP) secretary-general Chaithawat Tulathon said the party's MPs would discuss whether to vote for Pheu Thai's PM candidate on Tuesday.
He said MFP MPs would vote in accordance with the party's stance instead of exercising their own judgement, and when asked about the suggestion that the MFP should vote for Pheu Thai so the Senate's votes were not needed, shot back with the question. "Why didn't Bhumjaithai vote for the MFP-led bloc to switch off the Senate?"