The term "executive power" Article II, Section 1, Clause 1 of the Constitution, refers to the title of President as the executive. He is instructed therein by the declaration "take Care that the Laws be faithfully executed" made in Article II, Section 3, Clause 5, else he faces impeachment.

An executive order of the President must find support in the Constitution, either in a clause granting the President specific power, or by a delegation of power by Congress to the President.  more at url