BJP president Rajnath Singh and Shiv Sena executive president Uddhav Thackeray would launch the saffron alliance's poll campaign in Mumbai on March 20.
The two leaders would address a convention of Sena-BJP functionaries and people's representatives at Sewree, Sena sources said.
Maharashtra BJP president Nitin Gadkari, general secretary Gopinath Munde and senior Sena leader Manohar Joshi would also address the gathering.
The alliance partners recently reached an understanding for jointly contesting the Lok Sabha polls. BJP would field candidates from 26 seats while the Sena would contest the remaining 22 seats in the state.