Hours after NCP leader Ajit Pawar joined hands with the BJP to form government in Maharashtra, Congress leader Yashomati Thakur said what happened was "unconstitutional" and "misuse of power".
NCP's legislature party leader Ajit took oath as the deputy of Chief Minister Devendra Fadnavis on Saturday morning.
NCP chief Sharad Pawar has already said Ajit's decision was his "personal and not the party's".
"What has happened is unconstitutional. It is misuse of power," Thakur told reporters here, attacking the BJP.
Meanwhile, NCP workers raised slogans against Ajit as they rallied behind Sharad Pawar.