Uddhav Thackeray addressed supporters from the sunroof of his car.
Former Maharashtra Chief Minister Uddhav Thackeray on Saturday raised the pitch of his attack on the Election Commission, a day after it awarded the Shiv Sena party name and bow-and-arrow symbol to his rival and successor Eknath Shinde.
"The Election Commission, PM [Narendra] Modi's slave, has done something that has never happened before," he said, urging his supporters to be patient and prepare for the next elections - the high-stakes contest for Mumbai's civic body BMC.
Mr Thackeray addressed a large crowd assembled as a show of strength outside Matoshree, the family home of the Thackerays.
He stood out of the sunroof of his car, evoking the image of his father Bal Thackeray, who famously used to address followers from the roof of his car in the party's early days.
The party's symbol has been "stolen" and the "thief" needs to be taught a lesson, Uddhav Thackeray said, a remark aimed at Mr Shinde, the Maharashtra Chief Minister.
A huge crowd of supporters gathered outside Matoshree, the family of the Thackerays.
In a big blow to Mr Thackeray, the Election Commission on Friday handed over the identity of the party, which his father had founded in 1966, to Mr Shinde, capping a coup that is now nearly eight months old.
Mr Thackeray's team, who had urged the Election Commission to wait for a Supreme Court verdict in the case, has said they will challenge the decision in the top court. The tussle between the two sides is being heard by the Supreme Court.
Mr Shinde had mounted a rebellion in June, flying away with over 40 Sena MLAs with the help of the BJP, and triggering the eventual ouster of Mr Thackeray's government that included two ideologically disparate allies in the Congress and the Nationalist Congress Party.
In a 78-page order on the protracted battle for control of the party, the Election Commission said Mr Shinde was supported by MLAs with 76 per cent of the party's winning votes in the 2019 Maharashtra assembly polls.
The poll body said the Uddhav Thackeray faction can keep the name 'Shiv Sena Uddhav Balasaheb Thackeray' and the 'flaming torch' symbol assigned last year.
Eknath Shinde welcomed the move as a "victory for democracy" and, protesting Mr Thackeray's characterisation of him as a "traitor", said his rival needed to "introspect".