Its laughable to compare US house of reps to Indian parliament where every political party is busy looking after their electoral interest national interest be damned. In the US there is a age old tradition of parties rising above narrow partisan interest because national interest does matter come election time in the US. Left doesn't care a hoot about national interest, BJP knows that most people doesn't quite understand the implications of this deal and Indians are used to having opposition parties who oppose for the sake of opposition; so BJP has little to lose and much to gain from Congress bungling. Based on your assertions it seems you are opposed to Congress which is perfectly fine, but it seems your opposition to Congress is blinding you to the merits of the deal. You need to separate the deal from Congress party and view the deal in larger national interest.
Finally, BJP by publicly offering to work with the govt on the deal stands to gain a lot of goodwill and if Congress refused to be reasonable in working with BJP on the issue then it stands to look petty and selfish. Think about it.
