Rahul Gandhi said the yatra is like a 'tapasya' to him

"India is the institutions that protect this flag. India is free media that protects this flag. India is a judiciary that protects this flag. And today every single one of our institutions is under attack by BJP, RSS. They think this flag is their personal property. They think they can determine single-handedly the future of this people, state of this country," Rahul Gandhi said in his address.

The BJP, RSS think they can "frighten opposition using ED, CBI, Income Tax," Mr Gandhi said. "It doesn't matter how many hours of interrogation they do, not a single opposition leader is going to be scared of BJP," he added.

Dubbed the "longest march" in the country over a Century by the Congress, the Bharat Jodo Yatra was launched with a rally in Kanyakumari. The 'padyatra' or foot march will begin on Thursday morning. The 3,500-km foot march will be covered in 150 days.

Leaders of the Congress have denied any political angle and insisted that the yatra "is meant to unite the country". During the march, they will try to connect with the common people on various issues, including inflation, price rise and unemployment, the leaders have said.

Pointing to the multiple defections in the recent weeks, the BJP insisted that the Congress should prioritise patching up the party. "I think that instead of doing the Bharat Jodi Yatra, Rahul Gandhi ji should do a 'Congress Jodo Yatra'. Prime Minister Narendra Modi is working to connect the country," the BJP's Ramdas Athawale was quoted as saying by news agency ANI.

Congress chief Sonia Gandhi, unable to attend the launch due to health issues, said in a statement that she will be participating "in thought and spirit". "This is a landmark occasion for our great party with such a glorious legacy -- the Indian National Congress. I am confident that our organization will be rejuvenated," she added.

Senior party leader Jairam Ramesh said that a stronger Congress is a must for opposition unity against the BJP. In a tough message to the regional parties, he added that the Congress cannot be taken for granted by the other opposition parties.

The Yatra comes amid the Congress's efforts to hold internal elections, which have been repeatedly postponed due to Mr Gandhi's reluctance to participate. A section in the party is hoping for a continued leadership by the Gandhis.

Rahul Gandhi started the day with a visit to his father Rajiv Gandhi's memorial in Tamil Nadu's Sriperumbudur, where the former Prime Minister was killed in a suicide attack on May 21, 1991.

Mr Gandhi will walk all the way - from Kanyakumari to Kashmir, where the yatra will conclude. He will be staying in a shipping container cabin, which will have a bed, toilet and an air conditioner. Containers have been set up for other yatris as well, who will walk the entire route with Mr Gandhi, sources said.

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