PC Chacko, the head of the joint parliamentary panel probing the telecom scandal, was on Tuesday forced to call off a scheduled meeting of the committee because of the stand-off between Congress and BJP over the list of witnesses to be summoned. Chacko had on Monday night met senior BJP leader Yashwant Sinha with a list of witnesses, including former prime minister AB Vajpayee and former defence minister George Fernandes, both of whom are ailing.