It's political blackmail of the darkest kind. Tamil Nadu CM M Karunanidhi warned the Prime Minister that if the government sold the 10 per cent stake in TN based Neyveli Lignite Corporation, then southern parties like the DMK will withdraw support from the UPA government. "When the Union Government is not in a position to accept the demand of the NLC workers, the DMK is thinking whether to continue in the Union government and be a party to the decision of the Union Government.