Sources said the party would start its campaign for the coming elections by paying homage to Thackeray, the late Sena patriarch.
The elections are being seen as a big test for Uddhav Thackeray, who took over as president of the party after his father's death.
Preparations for the Lok Sabha and Maharashtra Assembly polls had already begun, a Sena leader said.
Republican Party of India (Athawale group) and Raju Shetty-led Swabhimani Shetkari Sanghtana are the two new members of the Sena-BJP's alliance in Maharashtra this time.
Sena and BJP are trying to woo other regional parties too. Senior BJP leader Gopinath Munde had confirmed last week that talks were on with Peasants and Workers Party (PWP).
Seat-sharing talks between the alliance partners will start on January 14.
