A 25-year-old man in Tamil Nadu's Erode had also set him ablaze on Thursday allegedly over the central and state governments' "inaction" on the Cauvery issue, police said. He sustained 90 per cent burns.
MDMK leader Vaiko has appealed to people not to harm themselves and protest in a peaceful way.
Mr Vaiko said Saravana Suresh, his wife's nephew, had been upset for farmers and the state. On Friday, Mr Vaiko said, Suresh, 50, left his home in Virudhunagar, over 500 km from state capital Chennai, for his morning walk. When he reached an open ground, he reportedly doused himself with kerosene and set himself on fire, IANS reported. Passersby rushed him to the Virudhunagar government hospital with 80 per cent burns. He was later shifted to Madurai's Apollo Hospital.
"I have lost hope of his survival. All in my family are suffering... (because of the incident)," Mr Vaiko added.Tamil Nadu political parties, farmer associations and various other bodies have been protesting against the central government for not setting up the Cauvery Management Board on an urgent basis.
The Supreme Court had on February 16 reduced Tamil Nadu's share of Cauvery water and given more water to Karnataka and ordered the centre to set up the board within six weeks. The deadline, however, expired on March 29 and no action was taken forcing people to raise their concern through various protests.
They have been alleging that the ruling BJP has been "deliberately" delaying the board as it could upset poll-bound Karnataka and has an impact on the election results for the party.
Angry protesters even forced all Indian Premier League (IPL) matches scheduled to be held in Chennai to shift to Pune. Superstar Rajinikanth, who announced his political entry on December last year, had emphasised that holding cricket matches when Cauvery protests are on, is an "embarrassment".
Prime Minister Narendra Modi, who was in Chennai two days ago to inaugurate DefExpo, was shown black flags and black balloons by protesters.
Actor-turned-politician Kamal Haasan too "welcomed" PM Modi and attempted to draw his attention to the "crisis" in Tamil Nadu due to the delay on part of the centre through a video message in which he said that "people are more important than the elections" .
Kamal Haasan had earlier held politics responsible for the delay since neighbouring Karnataka is set to vote its next government in May.Last week, he told TheIndianSubcontinent that the centre was playing a political game that was standing in the way of the state receiving justice.
The ruling AIADMK and the opposition parties, including DMK, had called for state-wide bandh and hunger strike earlier this month to register their protest.