The sooner he quits, the better it would be for the country.
No doubt, Congress is trying to blackmail the Communists. Many experts including several former Chiefs of Atomic Energy Commission have opined that India will be selling itself to US if it goes ahead with the 123 Nuclear Deal. But the Congress is hell bent on signing the agreement which is heavily loaded against the interests of the country. A detailed analysis of the text of the agreement and the Hyde Act will reveal even to an imbecile as to how US could armtwist India including making India to agree for any future sanctions against Iran.
Considering all these aspects, it would be better if this lameduck PM resigns and salvages at least some self respect.