INTERNATIONAL AGREEMENTS WITHOUT SENATE APPROVAL
The capacity of the United States to enter into agreements with other nations is not exhausted in the treaty-making power. The Constitution recognizes a distinction between ''treaties'' and ''agreements'' or ''compacts'' but does not indicate what the difference is.
388 The differences, which once may have been clearer, have been seriously blurred in practice within recent decades. Once a stepchild in the family in which treaties were the preferred offspring, the executive agreement has surpassed in number and perhaps in international influence the treaty formally signed, submitted for ratification to the Senate, and proclaimed upon ratification.
Sorry, nothing in there about 2/3 no longer needed. Got anything else?