Shiv Sena UBT chief Uddhav Thackeray offered to step down during the party's 60th foundation day address in Mumbai.
The offer follows the absence of six party MPs from the event, sparking intense speculation of their defection to Eknath Shinde's faction.
Thackeray apologised to the electorate who voted for the six missing lawmakers in the 2024 Lok Sabha elections.