Can the President refuse to take the oath or affirmation before entering upon his office?
No, the President cannot refuse to take the oath or affirmation before entering upon his office. The context states that "Every President and every person acting as President or discharging the functions of the President shall, before entering upon his office, make and subscribe in the presence of the Chief Justice of India or, in his absence, the senior-most Judge of the Supreme Court available, an oath or affirmation."