Nitsh Kumar has also invited Prime Minister Narendra Modi for the oath function in Patna.
The fifth oath ceremony of Bihar chief minister Nitish Kumar -- a political arch-rival of Prime Minister Narendra Modi -- is providing ample opportunities to the anti-BJP brigade to congregate. The exception will be BJP ally Shiv Sena, which, however, is known for being at odds with the BJP.
Prominent among Mr Kumar's anti-BJP guests will be Delhi Chief Minister Arvind Kejriwal, who has been at loggerheads with the Narendra Modi government over a range of issues after decimating his party in the assembly elections earlier this year.
The other will be West Bengal Chief Minister Mamata Banerjee, who will be taking on the BJP in the state elections next year.
The guest list of the big day looks like a who's who of the opposition. From the Congress, high profile leaders like vice-president Rahul Gandhi, Kerala Chief Minister Oommen Chandy and Himachal Pradesh Chief Minister Virbhadra Singh will attend.
Other anti-BJP voices likely to be in Patna on Friday include former Tamil Nadu chief minister and DMK patriarch M Karunanidhi's son MK Stalin and former Jammu and Kashmir Chief Minister Omar Abdullah.
Uttar Pradesh Chief Minister Akhilesh Yadav will also attend the ceremony, despite the Samajwadi Party's split from the Nitish Kumar-Lalu Prasad Grand Alliance ahead of the assembly polls in Bihar. Assembly elections are due in Uttar Pradesh in 2017.
"A broad coalition of opposition forces is working together anyway. It will be a good opportunity for them to meet," said Ajay Alok, spokesperson of Mr Kumar's party, the Janata Dal (United).
The odd-one-out at the gathering will be the Shiv Sena, which governs Maharashtra along with the BJP and is an ally at the Centre.
But the Sena has made news for not seeing eye-to-eye with the BJP on a range of issues. Even in the aftermath of the Bihar elections, it had heaped praise on Nitish Kumar more than once.
Though party chief Uddhav Thackeray is not coming, two Maharashtra ministers are likely to attend.
Nitish Kumar has invited Prime Minister Narendra Modi to the ceremony too. He is sending two ministers. Both sides say this is normal courtesy.