Sanctions on Iran - Battle in the Senate

Numerous sources (here, here, here too) reported last week the GOP-led Congress intends to move to increase sanctions against Iran, as well as a vote on any Iran/P5+1 deal.  When asked for comment onthe scope of the santions, Senate Foreign Relations Committee Chair Bob Corker replied it will not be "your mother's sanction bill."  UN Ambassador Powers urged Congress to hold off.  But santions are not limited to the GOP -- Democratic Senator Bob Menendez is drafting bi-partisan legislation, "but only in the event that no deal is reached by the June deadline established by the international coalition that is pressing Iran."  Senators opposed to sanctions are mounting a counter.  CNN explains why this is a big deal.