BJP will gain the most out of the actions of left parties. Most likely the US senate will take up the deal only after their elections. Thanks to the anti incumbency factor Congress will lose and BJP will come to power. BJP will renegotiate and sign the deal with the new US government and claim all the credit after all the hard work put in by Manmohan Singh.
The real motive of the left parties was to humilate congress before the elections. The left very well knows that congress is going to come back with reduced numbers in the elections whereas their share of seats is not going to be much affected (maybe it will reduce from 60 to 40). Left regards the congress as their main political adversaries. The communist elsewhere has also regarded social democrats as their main adversaries.
