Fifteen cabinet ministers resigned on Tuesday to take up seats in the new senate, as the Pheu Thai Party questioned the impartiality of the nominations made by a selection panel appointed by Deputy Prime Minister Prawit Wongsuwon.
Those who resigned included Deputy Prime Minister and Justice Minister Prajin Juntong, Deputy Prime Minister Chatchai Sarikulya, Prime Minister's Office Minister Suwaphan Tanyuvardhana, Natural Resources and Environment Minister Surasak Karnjanarat, Labour Minister Adul Sangsingkeo, Education Minister Teerakiat Jareonsettasin, Deputy Education Ministers Surachet Chaiwong and Udom Kachintorn and Deputy Foreign Minister Virasakdi Futrakul.
The others were Tourism and Sports Minister Weerasak Kowsurat, Deputy Agriculture and Cooperatives Minister Luck Wajananawat, Deputy Industry Minister Somchai Harnhirun, Deputy Interior Minister Sutee Markboon, Social Development and Human Security Minister Anantaporn Kanjanarat, and Deputy Finance Minister Wisudhi Srisuphan.
Prime Minister Prayut Chan-o-cha posed for photos with the 15 ministers during a break of the cabinet meeting on Tuesday.
At the head office of the Pheu Thai, legal affairs chief Chusak Sirinil said the party wrote to each of the election commissioners, asking them to revoke the senate nominations.
The constitution required the senate selection committee to be politically neutral, but the selection committee was chaired by Deputy Prime Minister Prawit Wongsuwon, Mr Chusak said.
"We see a movement to maintain power. It is to appoint a number of people who will vote for the prime minister. Soon 250 senators will take part in the voting, together with 500 MPs. Everything is clear," he said.
Earlier on Tuesday it was revealed about 60 members of the National Legislative Assembly were resigning to accept appointment to the new senate.