Thaksin is the brother of Prime Minister Yingluck Shinawatra and widely viewed as the de facto leader of the ruling Pheu Thai Party.
The source said Thaksin also plans to ask Metropolitan Police Bureau chief Kamronwit Thoopkrachang to join Pheu Thai after he retires from the police force next September.
Mr Panthongtae has been getting more involved in politics in recent years, taking part in Pheu Thai activities and defending the government, his father and his aunt, Ms Yingluck.
He has used his Facebook page to counter their political opponents, including the Democrat Party.
Mr Panthongtae appears to have shaken off his playboy image as he is currently travelling to whip up support for people in provinces ravaged by the flood crisis.
Political observers believe Mr Panthongtae may decide to enter politics to take on the political mantle of the Shinawatra family, the source said.
The source added Thaksin is still considering whether to field his son to run in Chiang Mai or to have him as a list MP.
Pheu Thai list-MP and red shirt co-leader Cherdchai Tantisirin Sunday voiced his support for Mr Panthongtae to enter the political arena.
He said Mr Panthongtae has what it takes to be a good politician as he is popular and democratically minded.
The source said if the government can complete its four-year tenure, which expires in 2015, many high-ranking officials who will retire next year will be approached to join Pheu Thai ahead of the next general election. Pol Lt Gen Kamronwit is among them.
The source said Thaksin and his other younger sister, Pheu Thai MP for Chiang Mai Yaowapa Wongsawat, want to approach Pol Lt Gen Kamronwit to join the party after he retires, either as a list MP or to contest Pathum Thai in the next election.
Pol Lt Gen Kamronwit is known to have close ties to Thaksin and is a native of Pathum Thani.
Thaksin is also considering making Pol Lt Gen Kamronwit deputy prime minister in charge of the police force after the next election, the source said.
But Pol Lt Gen Kamronwit said Sunday the Pheu Thai Party had not yet approached him, and he had no plan to enter the political arena.
The source said Thaksin recently told Pheu Thai MPs to brace themselves for a possible snap election amid pressure from anti-government elements seeking to overthrow the administration.
The source said Pheu Thai MPs and some cabinet ministers flew to Macau and Hong Kong late last month to visit the former prime minister, who has remained overseas in self-imposed exile since receiving a jail term in 2008 over the Ratchadaphisek land deal case.
The source said Thaksin stressed the need for the MPs to regularly visit their constituents to prepare for a possible snap election at short notice.
This is because "internal and external factors" are bent on toppling the government, the source quoted Thaksin as saying.
Even though the Constitution Court last week ruled in favour of the government's 2014 budget bill and its charter amendment draft seeking to change the composition of the Senate, the government cannot afford to be complacent, the source said.
In the first ruling, the court dismissed the petition filed by the Democrats and senators to seek an injunction to suspend Ms Yingluck's submission of the amendment draft for royal endorsement after it was passed by parliament.
In the other case, the court ruled unanimously by a vote of 8-0 that the 2014 fiscal budget bill did not violate the charter, as claimed by the Democrats and a group of anti-Thaksin senators.
But the charter court is yet to rule on whether the charter amendment draft is unconstitutional, as claimed by the opposition.
The source said Pheu Thai will conduct a survey in several provinces to gauge constituents' views on the performance of their MPs and ask them if they would want the party to field the same MPs in the next general election.
The source noted that Pheu Thai's support base in Pathum Thani has been eroded significantly since the province was devastated in the 2011 flood crisis.
After the floods, Sumeth Riddhagani resigned as MP for Pathum Thani's Constituency 5 to contest the election of the Pathum Thani provincial administrative chief.
But he was defeated by Democrat-allied independent Chan Puangpetch.
Thaksin has recently been in conflict with the Harnsawat family, headed by former deputy interior minister Chuchart Harnsawat, which has long enjoyed local support in Pathum Thani.
To regain its lost footing in the province, the Pheu Thai Party must now seek new candidates to run in constituencies 4, 5 and 6 of Pathum Thani in the next election, the source said.