From left: Ex-premier Somchai Wongsawat, Thaksin favourite Khunying Sudarat Keyuraphan and ex-drug fighting policeman Seripisuth Temiyavej. (Bangkok Post file photos)

While it looks calm publicly, political undercurrents in the Pheu Thai Party is moving toward selecting a new leader to steer the former ruling party to compete in a general election expected late next year.

Despite a ban on political activities by order of the regime, the party's factions are eagerly testing the waters over who to pledge support to as the new party leader.

See also: Political meeting rousted, Prawit issues warning

But contrary to past elections, a political party leader under the 2017 constitution is crucial as he or she has to be publicly nominated by the party to be prime minister if the party wins the elections.

An internal survey showed if elections were to take place today, Pheu Thai would have the highest number of MP seats and would potentially form a government.

But it seems ousted prime minister Thaksin Shinawatra, who is believed to be the Pheu Thai de facto leader, is caught in a bind trying to sort out demands from his family members.

Last week, two new names were mentioned in local media as potential candidates to lead the Pheu Thai Party. They are former foreign minister Surakiart Sathirathai and former national police chief Seripisuth Temiyavej.

Mr Surakiart immediately came out to deny the reports but Pol Gen Seripisuth has yet to respond on the issue.

Party insiders admitted that Pol Gen Seripisuth really does have the support of some party members, thanks to his actions in launching a series of criticism against the National Council for Peace and Order (NCPO) and the government.

Pol Gen Seripisuth had blasted the regime for invoking Section 44 of the interim charter to raid Wat Phra Dhammakaya. He had also slammed the government for buying Chinese submarines and, most recently, he criticised the regime's poor performance over the three years since the coup d'etat.

Pol Gen Seripisuth also caught the eye of party members because of his connections with former classmates of Thaksin, who graduated from the Armed Forces Academies Preparatory School.

But it won't be easy for Pol Gen Seripisuth to be selected as the new party leader.

Party sources said that so far there are three contenders to be the new leader. Besides Pol Gen Seripisuth, who is supported by "hard-core" party members interested in directly fighting the regime, the two others are Khunying Sudarat Keyuraphan, a key party member, and Somchai Wongsawat, a former prime minister and Thaksin's brother-in-law.

Khunying Sudarat has emerged as a strong candidate for the role. With her clear vision, political experience and compromising personality, she has been eyed by Thaksin as a potential leader at this crucial time, when the party needs someone who can mobilise resources to fight in a political campaign and, most importantly, gain the regime's acceptance.

What made it quite clear that Khunying Sudarat is poised to win Thaksin's support to lead the party was the reopening of a room that used to function as the nerve centre of the Pheu Thai headquarters.

A source said the office on the 8th floor of the Bangkok headquarters -- reserved as a private room for Thaksin and closed for years since the former premier was ousted in the military coup in 2006 -- was recently unlocked for Khunying Sudarat to use. She also currently chairs party meetings.

Even acting Pheu Thai leader Pol Lt Gen Viroj Pao-in uses an adjacent room.

However, the road to party leadership for Khunying Sudarat is not so smooth either. Other key members of the Shinawatra family have not supported her.

According to sources, party influencer Yaowapa Wongsawat wants her husband Somchai to be the party leader, insisting that Mr Somchai, the former prime minister, has done nothing wrong.

Mr Somchai was forced to step down from the premiership after the Constitutional Court dissolved the People's Power Party, of which he was the leader, in 2008.

Former prime minister Yingluck Shinawatra, Thaksin's sister, supported her elder sister's demand, according to sources.

But some party members do not agree with that option, saying the party would then be unable to distance itself from the Shinawatra family.

In addition, since Mr Somchai's fate remains uncertain as a court case involving the Somchai government's dispersal of yellow-shirt protesters in 2008 is ongoing, he has a slim chance of becoming the new party leader.

Ms Yaowapa and Ms Yingluck are poised to support Pol Gen Seripisuth if Mr Somchai fails to win the top post, sources said.

How can Thaksin find a balance between his plan and his sisters' demands?