He said MPs from SJB signed the motion yesterday and other MPs in the opposition are expected to submit their signatures today, he said.
His remarks comes as SLPP General Secretary Sagala Kariyawasam reiterates that he would stand by the letter released by him demanding the resignation of Gammanpila.
Kariyawasam has said his party would stand for the public and that there is no any issue over his statement within the party.
Kariyawasam said so after attending a party meeting yesterday. About 23 backbenchers of the SLPP had attended the meeting.