Nor is Shiv Sena's traditional appeal to Mumbai natives who speak the local language enough to guarantee power.
As Shiv Sena looks to update its image, such campaigns are likely to be rarer.
The charismatic prime minister, Narendra Modi, has countered the Thackerays' own personal appeal while nearly three decades of Shiv Sena control of Mumbai's town hall has disappointed many in the city.
Thackeray says the Shiv Sena is working to train thousands of young people for jobs in sectors such as banking and in languages.
Analysts say the BJP, which also follows a rightwing Hindu nationalist ideology, has cut deep into Shiv Sena's core support with its promise of economic development and opportunity.
In state elections earlier this month, the Shiv Sena – the name means "warriors of Shivaji" (a former ruler of the region) – lost ground to the Bharatiya Janata party (BJP), which won power at a national level with a landslide victory in May.
Bassi said officials were also seeking to establish how the alleged rapist, named as Shiv Kumar Yadav, obtained a police certificate showing a clean criminal record.
But after three decades of dominance of municipal politics, the Shiv Sena is, like so much in India, in transition.
There is also an effort to forget the "moral policing" of the past, when Shiv Sena activists harassed couples in parks.
It is equally unclear whether the crucial youth vote will swing Shiv Sena's way, despite Aditya Thackeray's youth and his tours of small towns.
The portrait of the family patriarch, Bal Thackeray, a cartoonist turned rightwing populist politician who founded the Shiv Sena organisation in 1966 and led it until his death two years ago, is everywhere: hung in offices in slums, on the walls of cheap restaurants, beside temples.
