Final answer:
In the constitutional text of the presidential oath of office, the 6-letter word is 'swear'. This underscore the President's commitment to the Constitution, and the same principles extend to other federal officials, reinforcing the secular governance and constitutional supremacy in the United States.
Step-by-step explanation:
The constitutional text of the presidential oath of office is a statement that the President must make before assuming office. The oath as stipulated in Article II, Section 1, Clause 8 of the U.S. Constitution is: "I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States." Thus, the answer to the question in the constitutional text of the presidential oath of office, a 6-letter word that fits the context is 'swear'.
This particular clause and the need for an oath or affirmation underscore the importance of the Constitution as the supreme law of the land, and the commitment required from the President to uphold its values. The presidential oath of office is traditionally taken during the inauguration ceremony, and all other federal officials, according to Article VI, Clause 3, must also take an oath or affirmation to support the Constitution, highlighting the secular nature of the Republic and the separation between church and state.