Congress president Sonia Gandhi described the "Bharat Jodo Yatra" on Wednesday as a landmark occasion and hoped that the 3,500-km foot march would help rejuvenate the party.
In her message read out at the rally in Kanyakumari, Mrs Gandhi said she would be participating in the yatra daily in thought and spirit.
"In view of the medical check-ups that I am undergoing, I regret my inability to be with all of you in person this momentous evening to launch the historic Bharat Jodo Yatra from Kanyakumari to Kashmir," Sonia Gandhi said.
"This is a landmark occasion for our great party with such a glorious legacy -- the Indian National Congress. I am confident that our organisation will be rejuvenated," Mrs Gandhi said in her message.
She also described the occasion as a "transformational moment in Indian politics".
Mrs Gandhi congratulated the 120-odd party colleagues who will complete the entire "padyatra" and said there will be hundreds and thousands of others who will join the march in different states.
"I extend my greetings to them as well," she said.
"Speaking for myself, I will be participating in the Bharat Jodo Yatra daily in thought and spirit. I will, of course, be seeing the yatra live as it progresses. So, let us move forward united and firm in our resolve," the Congress president said.
The occasion also saw the handing over of the national flag to officially mark the start of the "padayatra", which the Congress has described as the longest ever undertaken by any political party in independent India.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
