The new cabinet list has been submitted for royal endorsement, Pheu Thai Party sources said.
While there was no official word on why they were present at Government House, some of the group admitted they were asked to drop by to fill up forms that would allow the government to examine their qualifications.
The rejig is likely to be a major one, affecting at least 10 ministerial posts.
Several former banned politicians from the so-called House No.111 appear poised to take up several ministerial posts in the new-look cabinet.
Among the potential new entrants are Phongthep Thepkanchana, Varathep Rattanakorn, Sermsak Pongpanit, Pongsak Raktapongpaisal, Yutthapong Charassathien, Prasert Chantararuangthong and Thitima Chaisaeng.
Some current cabinet ministers also dropped by Government House to fill out forms, leading to speculation that they would be changing posts.
Among them were Deputy Interior Minister Thanit Thienthong, Deputy Transport Minister Pol Lt Gen Chatt Kuldiloke, Deputy Transport Minister Chatchart Sithipan, Deputy Agriculture Minister Nattawut Saikuar and Transport Minister Jarupong Ruangsuwan.
Mr Jarupong is expected to be made interior minister while Mr Chatchart is expected to be nominated as transport minister, Pheu Thai sources said.
Mr Pongsak is expected to be appointed deputy prime minister and energy minister, and Mr Phongthep is expected to replace Suchart Thada-Thamrongvech as education minister.
On the coalition front, Agriculture and Cooperatives Minister Theera Wongsamut has decided to step down and nominate Yukol Limlaemthong as his successor, Pheu Thai sources said. Phalang Chon Party plans to appoint Sonthaya Khunploem to replace his wife Sukumol Khunploem as the culture minister, they said.
Former national police chief Pol Gen Priewpan Damapong and red-shirt core leader Jatuporn Prompan, both of whom were widely expected to take up ministerial roles in this reshuffle, have not been included on the new cabinet list.
Deputy Transport Minister Pol Lt Gen Chatt Kuldiloke said he heard that he would be relieved from his post. "If I am really sacked from a cabinet post in this reshuffle, I will go back home and still work for the party," he said.
Meanwhile, Democrat leader Abhisit Vejjajiva yesterday called on the government to hear a censure debate before proceeding with the shake-up.
The government's opponents have claimed that the reshuffle is aimed to deflect attention away from the planned no-confidence debate.
"I don't know if there is an urgent need for a reshuffle now. The government can wait until after the censure debate to proceed," Mr Abhisit said.
"There are a lot of issues to be addressed first, such as reconciliation and the rice pledging policy."
Asked if the reshuffle would affect the planned censure debate, Mr Abhisit said he would have to see the new list.
However he said he hoped the government would not exclude any ministers targeted in the debate after the submission of the motion.
The opposition will table a no-confidence motion against the government by Oct 31.