Amendment XXIII

1. The District constituting the seat of Government of the United States
shall appoint in such manner as the Congress may direct: A number of electors
of President and Vice President equal to the whole number of Senators and
Representatives in Congress to which the District would be entitled if it
were a State, but in no event more than the least populous State; they shall
be in addition to those appointed by the States, but they shall be
considered, for the purposes of the election of President and Vice President,
to be electors appointed by a State; and they shall meet in the District and
perform such duties as provided by the twelfth article of amendment. 

2. The Congress shall have power to enforce this article by appropriate
legislation.