The four ministers who formed the Palang Pracharath Party resigned from the cabinet on Tuesday.
Commerce Minister Sontirat Sontijirawong, Science and Technology Minister Suvit Maesincee, Industry Minister Uttama Savanayana and PM's Office Minister Kobsak Pootrakool tendered their resignation letters, effective Wednesday, to Prime Minister Prayut Chan-o-cha at Government House.
Mr Sonti, secretary-general of Palang Pracharath, said their resignations set a precedent because the politicians who criticised their dual roles as cabinet ministers and campaigning politicians had never done the same.
He also said the the four men had never discussed political issues during their official work hours.
The four said they resigned because their tasks as ministers were finished. They could now fully commit to their political activities.
Mr Uttama is the leader of Palang Pracharath, Mr Suvit is deputy leader and Mr Kobsak the part spokesman.
They did not say who would be the party's candidate for prime minister.