"I am deeply concerned and saddened by the current scenario in the party and the state government," Rio, who is contesting the Lok Sabha election, said in a statement here last night.
Stressing that he is contesting the LS polls to take up bigger responsibilities for the state and North East, he said "at this crucial juncture it is of paramount importance that the NPF stays united for the sake of the people who have given their mandate to us."
"The NPF led DAN Government must be able to provide a stable government under a spirit of unity, understanding and oneness," Rio said and appealed to partymen to come together to find a consensus solution which would pave the way for a smooth transition of power.
"The need of the hour is for us to come together, bury our differences and unify the party in the greater interest of the people," he said.
"The unity in NPF will further strengthen our common endeavour to take the peace process forward and bring permanent peace and political solution to our people," he said.
There are reports that two senior ministers - Minister for Planning and Coordination TR Zeliang and Minister for PHED Noke Wangno -- are in the race for the post of the chief minister.