"Digvijay's letter to me does not merit a response. Congress seems to be completely rattled and baffled. That is apparent from Digvijay's letter."
"Digvijay seems to be Congress's last resort," Kejriwal, who heads India Against Corruption (IAC), tweeted.
Responding to Singh's remarks, Kejriwal's close associate Kumar Vishwas said, "we have only one thing to say to him. Get well soon."
In a letter to Kejriwal, the AICC general secretary has described the activist as a "self-serving ambitious megalomaniac" having "streak" of Hitler in him.
Singh alleged that Kejriwal wanted him to recommend his name for being made a member of the National Advisory Council (NAC). Kejriwal later said to a news channel that the NAC members have no job apart from sipping tea with Congress president Sonia Gandhi. "I have no interest in having tea with Sonia Gandhi," he said.