Barrister Akere Muna made the revelation in Douala on Monday, after a tour of the city at the weekend. The leader of the Now Movement was speaking on Radio Balafon in the country in country's economic capital.
"I think there will be a coalition. Maurice [ chairman of The Cameroon Renaissance Movement] and I have discussed [...] it. Joshua [candidate of the Social Democratic Front] is someone I know. I know his family. I was even his lawyer in several cases, so it is not really a problem. I think we will find a solution [...]," he is quoted as saying by JournalduCameroon.com
"I urge Cameroonians to remain calm because we are aware of the urgency. We will come out with a solution," he has promised.
Maurice Kamto has previously reportedly declared his desire to form a coalition front as well.
Joshua Osih and Kamto are yet to react.
Some observers could see this as a good step forward to end the decades-long rule of Mr Biya who took over from Ahmadou Ahidjo in 1982.
Though it worked well in the Gambia against Yahya Jammeh, critics do not seem to see it materialise in Cameroon. Mr Biya often 'wins more than half of the votes all alone', leaving the rest of the parties with a very tiny, insignificant minority.
Mr Biya is yet to declare his candidacy for the election later this year. Several calls from across the country keep coming for him to run again for president.