Mamata Banerjee is seen to have projected herself as the pivot of a "non-Congress, non-BJP" grouping
The BJP's defeat in three big states energises the opposition just months before the 2019 polls but the Congress victory had acted as a downer for the proposed "maha gatbandhan" to take on Prime Minister Narendra Modi. Bengal Chief Minister Mamata Banerjee, the chief of the Trinamool Congress, is believed to have taken the lead in trying to band leading regional parties into a separate front to counter the Congress and negotiate with it.
The Congress, which had willingly taken a back-seat in the alliance in Karnataka, has been pitched firmly back at the centre of an opposition alliance for 2019 by their victories in the three heartland states. That is not seen as welcome news for regional leaders like Mamata Banerjee, who are vying for prominent roles in any united opposition front.
Sources say Ms Banerjee and the other leaders calculate more benefits in going into a coalition as a separate bloc - expected to give them a greater say and even bargaining power to project a regional leader as a possible prime ministerial candidate.
Ms Banerjee has already excused herself from attending Monday's round of oath ceremonies of Congress Chief Ministers. The other absentees will be Mayawati and Akhilesh Yadav, who, despite their last-minute support to the Congress in Madhya Pradesh and Rajasthan, are seen to have signalled their disapproval by begging off.
Over the past few months, Mamata Banerjee is seen to have projected herself as the pivot of a "non-Congress, non-BJP" grouping, with prominent one-on-one meetings with Chandrasekhara Rao, Mr Naidu and Mr Kejriwal.
Sources say those ready to join the club include Telangana's ruling TRS led by K Chandrasekhara Rao, Andhra Pradesh's ruling Telugu Desam Party (TDP) of Chandrababu Naidu, the BJD of Odisha chief minister Naveen Patnaik, Uttar Pradesh rivals-turned-allies Mayawati of the Bahujan Samaj Party (BSP) and Samajwadi Party leader Akhilesh Yadav and Arvind Kejriwal, the chief of the Aam Aadmi Party (AAP). Many of these leaders last came on a big stage during the Karnataka oath ceremony in May, which became an opposition success party.
Leaders like Mr Rao, Mr Kejriwal and Naveen Patnaik have never been comfortable with the idea of a front in which the Rahul Gandhi-led Congress is the leader, especially as the party is opposition in their states. The same goes for Chandrababu Naidu, though he buried his differences with the Congress to fight in Telangana against Mr Rao. In May, he and Ms Banerjee both pitched for regional parties to gather forces and consolidate their strength.
It is early days yet but the regional alliance, if it crystallises, is likely to damage the Congress' plans for Uttar Pradesh, where it wants an alliance with the Samajwadi Party and BSP for the 2019 national election.
Uttar Pradesh, with 80 parliamentary seats, is key to power for any political party. Most of these seats are currently with the BJP, with the Congress reduced to just two in the 2014 elections - the seats held by its top two, Rahul Gandhi and Sonia Gandhi.
The Samajwadi Party has already indicated it would like to be part of the opposition unity moves and is not sure of Mamata Banerjee's initiative to start another front.