Nwosu, whose emergence is being opposed by those who insist he was forced on the party, said only his candidature could guarantee a win for the party in the 2019 election.
He warned Oshiomhole not to take side with politicians working against the will of the people.
Nwosu told journalists in Owerri that such could jeopardise the chances of the party in the general election in the state.
He said: “The leadership of the party should not base their decisions on mere sentiments and propaganda perpetrated by the Abuja-based politicians who cannot even win their polling booths in an election.
“The question our party should be asking is, do we want to win this election and how do you win a general election, of course you must have the people with you and you must make sure that the people believe in you and not just staying in Abuja and making all the noise while you are not on ground.
“One challenge I have thrown to these people is that they should come home and let us put our popularity to test, let them organize a rally and let me organize one too and let us judge by the turn out, who is truly on ground and who is more popular.
“You don’t win elections on television or on the pages of newspaper, elections are done in the villages and Wards and not on Television, elections are not done in hotel rooms in Abuja either, they are done in the state. I challenge them to come to the state and test their popularity, this is where I am coming from.”