When the journalist informed Chennithala, the Congress leader was with UPA Presidential candidate Pranab Mukherjee, who is in Kerala for campaigning for Presidential poll, and Defence Minister AK Antony.
The Congress leader downplayed it but his close aides later informed the police in Kerala.
The threat call was in "Konkani-mixed Malayalam" and it allegedly came from Karnataka. The caller is said to have told the journalist that two persons have left from 'Bombay' to kill Chennithala.
Antony also spoke to the journalist to know more about the incident.