Outgoing Nagaland Chief Minister T R Zeliang today said he had submitted his resignation to Governor P B Acharya.
He told reporters that his party, the Naga People's Front (NPF), would play the role of a constructive opposition in the Assembly for the welfare of the state.
Zeliang had earlier claimed that he had the support of the majority of the MLAs in the House.
The NPF had won 27 seats in the 60-member state Assembly in the recently held election.
The BJP had yesterday announced that it had severed its 15-year-old alliance with the NPF and said it would go with its pre-poll ally, the NDPP. Former Chief Minister and NDPP leader Neiphiu Rio is expected to be sworn in on March 8.