Sonia Gandhi unveils M Karunanidhi's statue at DMK headquarters in Chennai

Congress chief Rahul Gandhi and his mother and UPA chairperson Sonia Gandhi were in Chennai after the party's big victory in the Hindi heartland in what is seen as another show of opposition strength. 

The occasion is the unveiling of a statue of DMK patriarch M Karunanidhi, who died in August after a long illness. The two leaders, who are attending the event after an invitation from Mr Karunanidhi's son MK Stalin, will share stage with him.

Andhra Pradesh Chief Minister Chandrababu Naidu, who has taken on the task of uniting the opposition against the BJP, was also present. West Bengal Chief Minister Mamata Banerjee, Kerala Chief Minister Pinarayi Vijayan and Puducherry's chief minister V Narayanasamy of the Congress, are expected to attend the programme as well.

The ties with the Congress and the DMK had been stable since 2004. The DMK, which been part of the UPA alliance, had broken off ahead of the 2014 Lok Sabha elections - with the result that neither party had won even one of 40 seats from Tamil Nadu.

But the two parties have been stable allies since. Rahul Gandhi had visited M Karunanidhi during his last illness and had attended his funeral.

The DMK chief is expected to attend tomorrow's oath ceremonies for Congress chief ministers in the Hindi heartland.