UNP General Secretary Akila Viraj Kariyawasam said the proposed new alliance led by the UNP would be formed soon.
Addressing a meeting, Kariyawasam said all democratic forces would extend their support to the alliance.
He also added that the Presidential candidate would be picked according to the accepted procedure within the UNP.
He previously ruled out the possibility of holding a secret ballot to choose the party's Presidential candidate.
According to the mechanism adopted by the UNP, the Presidential candidate of the party is chosen by the Working Committee.