The Uddhav Thackeray-led Maha Vikas Aghadi won the floor test in Maharashtra assembly on Saturday.
Governor BS Koshyari has asked Thackeray to prove majority by December 3.
NCP leader Dilip Walse Patil, who was appointed pro-tem speaker on Friday replacing Kalidas Kolambkar of the BJP, will conduct the floor test which will be held through a head count.
Thackeray was sworn-in as the chief minister on Thursday evening along with six other ministers - two each from the Sena, the Congress and the NCP. The MVA is an alliance of the Shiv Sena, NCP and the Congress.
Uddhav Thackeray-led alliance crossed the majority figure of 145 votes
Maha Vikas Aghaadi secures 169 votes in trust vote motion, proves majority.