Left parties do not have much credibility as regards nuclear deal or for that matter any foreign policy India needs to follow.Congress is national party and it knows what is in the interest of the country. It has been in the power and framed and entered insto a many deals albeit the mistakes made in the process. Left parties especially the CPM is not to be relied upon as they have extra-national agenda. And if you are strong enough no country can tie to any conditionality. So forget about left and proceed with the deal. It is not only bilateral but help seal international treaty in case of nuclear matters and India be a part in Nuclear suppliers group as a responsible and powerful in the comity of the world nations.