The party is now trying to poach MPs from two main factions inside the Bhumjaithai Party led by Somsak Thepsuthin and Sora-at Klinprathum to have the desired number of at least 300 seats.

Four political parties - Chartthaipattana, Chart Pattana Puea Pandin, Phalang Chon Party and Mahachon - have now agreed to join Pheu Thai to form a coalition government with 299 House seats combined.

The source said Pheu Thai is also seeking to control three major ministries - the Foreign, Defence and Interior ministries - which are crucial to bringing Thaksin back to Thailand.

However, the source said the party would tread carefully and not rush the plan to bring Thaksin back home considering that his opponents would come out in opposition to his return, which could rock the stability of the new government.

"The party will have to wait for the right timing when the new government becomes strongest with the support of more than 300 House seats to ensure the passage of legislation related to the granting of amnesty is plain sailing," the source said.

Pheu Thai will also need to be sure that its coalition partners will be given the cabinet seats they desire to guarantee government stability.

The Bhumjaithai Party, which looks likely to be on the opposition bench, is now facing possible dissolution as there have been complaints of election fraud against the party.

If Bhumjaithai is dissolved, the situation in parliament would be even more favourable to Pheu Thai as the opposition camp would be too weak while the government would be more stable. Then, it should be the right time to grant amnesty to Thaksin and bring him home, the source said. This scenario may take one to two years or even a full four-year term in office to materialise, but it is not too long and is seen to be "worth the wait", the source said.