Veteran politician Mallikarjun Kharge on Tuesday became the first non-Gandhi in 24 years to take over the reins of India's main opposition Congress party.

The 80-year-old was officially handed over the baton by interim president Sonia Gandhi at a function at Congress headquarters in the Indian capital this morning.

Sonia was the Congress president for nearly 23 years, while his son Rahul Gandhi held the coveted post for one year.

Addressing party leaders, Sonia said that she was "relieved" with Kharge taking over as Congress president.

"I did my duty to the best of my ability. Today, I will be freed of this responsibility. A weight is off my shoulder. I feel a sense of relief," Sonia said.

"This was a big responsibility. The responsibility is now on Mallikarjun Kharge," she said, adding that "the biggest challenge today was the crisis of democratic values in the country".

Kharge was elected the Congress president on October 19. Considered close to the Gandhi family, he defeated a relatively young Shashi Tharoor, a former UN diplomat, by a huge margin.

While Kharge is a staunch Gandhi family loyalist with 50 years of political experience, 66-year-old Tharoor is an articulate leader who joined the party in 2009 after nearly a 30-year stint in the UN.

Since Prime Minister Narendra Modi's nationalist BJP swept to power in 2014, the Congress has witnessed a vertiginous decline. The Congress is now in power only in a handful of Indian states.

Often blamed for the party's poor performance, Rahul has been reluctant to take over the reins of the party in the run-up to the general elections slated for 2024.