A showdown between Congress and the official auditor seems on the cards with Comptroller and Auditor General Vinod Rai refusing to resile from the 2G revenue loss estimates being pegged at between Rs 65,000 crore and a numbing Rs 1.76 lakh crore. The CAG is prepared to put up a stout defence of the auditor's methods and also fend off reports that he overruled retired official R P Singh - who led the 2G investigation - in quantifying revenue lost when he appears before the Public Accounts Committee.