All officers elected or appointed under or pursuant to this Constitution shall, before they enter on the performance of their public duties, severally take and subscribe the following oath or affirmation:

"I do solemnly swear (or affirm) that I will support the Constitution of the United States, and the Constitution of the Commonwealth of Virginia, and that I will faithfully and impartially discharge all the duties incumbent upon me as ...................., according to the best of my ability (so help me God)."