Answer:
commander in chief
Explanation:
Commander in chief is the role assigned to the US President in function. He then controls all branches of the US army (land, air, navy and now space).
chief executive is his role as leader as the White House, the executive branch of the government.
chief of party is is role within his political party, the Republicans for the current President.
chief legislator, as representing the executive branch, he's the one singing in to laws the bills adopted by the Congress.
