The decision by Yaowapa Wongsawat to quit politics is believed to be a new strategic move to make it appear that the last member of the Shinawatra clan has pulled out of the Pheu Thai Party, according to a political source.
However, not having membership of the party does not mean the influence of Ms Yaowapa, a younger sister of fugitive former prime minister Thaksin Shinawatra, over Pheu Thai will fade.
Questions from many political quarters persisted as to whether Ms Yaowapa, leader of the powerful Wang Bua Ban faction in Pheu Thai, is genuinely turning her back on the party and on politics after her sibling former premiers, Thaksin and Yingluck Shinawatra were ousted as prime ministers.
Ms Yaowapa, 62, is a "middle sister" between Thaksin, 68, and the youngest member of the generation, Yingluck, who is 50.
This week, Somchai Wongsawat, Ms Yaowapa's husband and a former prime minister, announced Ms Yaowapa decided not to validate her Pheu Thai party membership because she no longer wants to engage in political affairs.
The announcement was met with scepticism from politicians and scholars who thought the longtime Chiang Mai politician may still retain an active, behind-the-scenes role in the Pheu Thai Party.
To some observers, Ms Yaowapa retains two very different personas -- one where she comes across as having nothing to do with Pheu Thai and the other where she pulls strings behind the party while Thaksin lives in exile, according to Yutthaphon Itsarachai, a political scientist at the Sukhothai Thammathirat Open University.
His observation corresponds with a comment given by a Pheu Thai source who told the Bangkok Post Ms Yaowapa's role in the party will stay unchanged despite her void in membership.
She is always tagged with the thao kae, or boss, status with a right to own the party, the source said.
It is true Ms Yaowapa will, at least on paper, not be a Pheu Thai member any more.
However, there is no stopping her from continuing to exert power in the party through her husband or other key party members.
Mr Somchai is a party heavyweight who served as a prime minister for a short period of time in 2008.
Ms Yaowapa has controlled Wang Bua Ban since the faction formed part of the Thai Rak Thai Party, which was dissolved due to electoral fraud.
Thai Rak Thai was reborn into the People's Power Party, which was also ordered to disband also due to electoral fraud.
The Wang Bua Ban faction is believed to have more than 100 MPs under its wing, with strongholds in the North.
The Pheu Thai source views Ms Yaowapa's decision to keep a low profile as the right move to create the impression that the Shinawatras are no longer in charge of the party.
Ms Yaowapa is apparently playing safe, given prohibitions added to the organic law on political parties, Mr Yutthaphon said.
Under the law, a political party can be disbanded if it is directed or controlled by a person who has nothing to with the party.
Giving up party membership creates a convincing image, to some, of a Shinawatra-free Pheu Thai.
The law is based on the belief that Thaksin had made major decisions in the Pheu Thai Party over the past 10 years though he has lived in exile abroad after his escape from the Supreme Court's 2008 ruling which found him guilty of abusing of power by helping his ex-wife, Khunying Potjaman Na Pombejra, to buy prime land in the Ratchada area at a discount and sentenced him to two years in prison.
With the organic law enacted, Mr Yutthaphon said he is not surprised to see all the three siblings trying to distance themselves from Pheu Thai. Last month, during a trip to Japan, Thaksin insisted he had no involvement with Pheu Thai while his youngest sister, Yingluck has given no media interviews about politics in Thailand.
On Wednesday, it was Ms Yaowapa's turn to unveil the news that she too intends to keep out of the party's affairs.
But it is possible Ms Yaowapa will still give "advice" to her close associates and party members, Mr Yutthaphon said.
It would be natural for a respected figure like Ms Yaowapa to maintain an association with party members, Mr Yutthaphon said, adding it would be hard to determine that such an association constitutes an undue influence on the party's affairs, which is punishable under the organic law.
Within Pheu Thai, meanwhile, members who are legal experts will play more outstanding roles in managing the party. Among them are Chaikasem Nitisiri and Phongthep Thepkanjana.