KOLKATA: The Congress has a critical role in building opposition unity against the BJP, and efforts on this front could not hope to succeed without the Grand Old Party, National Conference chief and former Jammu and Kashmir CM Omar Abdullah has said.

"It (forming a Federal Front) is an ongoing process and as we get closer to general elections of 2019, I am sure it will take greater shape," he said. "You have seen a number of efforts were made by Sonia Gandhi to bring opposition parties together," he added, on the sidelines of a conclave on federalism in Kolkata on Saturday.

Abdullah's comments came a day after he met Trinamool chief and West Bengal CM Mamata Banerjee. "We were discussing how best the regional parties can come together to take on the Bharatiya Janata Party (BJP) in the forthcoming general elections," he said of the meeting, according to news agency IANS.

Abdullah also seemed to hint that the efforts at the so-called 'Federal Front' might not end up being the 'non-Congress, non-BJP' grouping that some leaders have been trying to pitch. "Obviously, no effort towards opposition unity will really succeed unless the Congress is also able to take the fight to the BJP the way we hope," he said.

A number of political leaders have expressed hope of building a 'non-Congress, non-BJP' political alliance ahead of the 2019 Lok Sabha elections. Telangana Rashtra Samiti (TRS) chief and Telangana Chief Minister K Chandrasekhar Rao has to this end held talks with a number of leaders, including Banerjee, JD(S) leader and former prime minister HD Deve Gowda, AIMIM chief Asaduddin Owaisi and JMM leader Hemant Soren.

KCR also refused to rule out the possibility of tying up with the Telugu Desam Party of Andhra Pradesh CM Chandrababu Naidu. The TDP and TRS have for long been on opposite sides of the highly-polarising demand for a separate Telangana. Now, with a separate state created, and with the TDP out of the NDA, the old foes could turn allies.

KCR had said there would be no significant change even if the Congress replaces the BJP in power, and that only the names would differ.

(With inputs from IANS)