Leaders from several non-BJP parties, which figure in opposition unity attempts ahead of 2019 Lok Sabha elections, are expected at the swearing in of Ashok Gehlot as Rajasthan chief minister on December 17.
Sachin Pilot will also be sworn in as the state's deputy chief minister at the 10 am ceremony to be held on the grounds of Albert Hall Museum, an iconic 19th century building.
The guest list is headed by Congress president Rahul Gandhi and includes former prime minister Manmohan Singh.
Others expected at the ceremony include Janata Dal (Secular) chief and former prime minister H D Deve Gowda, Loktantrik Janata Dal leader Sharad Yadav, National Conference's Farooq Abdullah and Telugu Desam Party's N Chandrababu Naidu.
Rashtriya Janata Dal's Tejashwi Yadav, DMK's M K Stalin and Kanimozhi, Jharkhand Mukti Morcha's Hemant Soren, Janata Vikas Morcha's Babulal Marandi and All India United Democratic Front leader Badruddin Ajmal are also likely to participate, Congress sources said.
The Congress won 99 seats and the BJP 73 out of the 199 where polling took place on December 7 for the Rajasthan assembly.
Both Gehlot and Pilot, who heads the Pradesh Congress Committee, were vying for the chief minister's post.