Raj left the Uddhav Thackeray-led party and founded MNS way back in 2005.
As Uddhav had emerged as a strong leader in the past few years, Raj should rejoin Shiv Sena, Athawale said, speaking to reporters here.
Talking about post-poll scenario in Kalyan-Dombivali Municipal Corporation, Athawale said his party would support Shiv Sena if BJP tried to win power by joining hands with Congress or NCP.