And on top of that, even if the above scenario was in place, Massachusetts has a nice habit of enacting ex post facto laws, similar to what they did after Ted Kennedy died. The law would be changed right after the election to ensure that “the will of the people of Massachusetts” was “respected.”
“Any member state may withdraw from this agreement, except that a withdrawal occurring six months or less before the end of a President’s term shall not become effective until a President or Vice President shall have been qualified to serve the next term.”
Any attempt by a state to pull out of the compact in violation of its terms would violate the Impairments Clause of the U.S. Constitution and would be void. Such an attempt would also violate existing federal law. Compliance would be enforced by Federal court action
The National Popular Vote compact is, first of all, a state law. It is a state law that would govern the manner of choosing presidential electors. A Secretary of State may not ignore or override the National Popular Vote law any more than he or she may ignore or override the winner-take-all rule that is currently the law in 48 states.
There has never been a court decision allowing a state to withdraw from an interstate compact without following the procedure for withdrawal specified by the compact. Indeed, courts have consistently rebuffed the occasional (sometimes creative) attempts by states to evade their obligations under interstate compacts.