US Presidents take an Oath of Office to defend the United States of America.
Part of defending is protecting national secrets, all of which are written down in documents.
The US government started classifying documents in 1951 and established a strict set of rules and regulations for the classification declassification and handling of national security information generated by the U.S. government and its employees and contractors, as well as information received from other governments.
The desired degree of secrecy about such information has three levels of classification: Confidential, Secret, and Top Secret.
Only people with a Top Secret Security clearance may view Top Secret documents. To get the clearance to view Top Secret documents an individual must undergo a thorough background check. National security eligibility determinations take into account a person’s:
- Stability
- Trustworthiness
- Reliability
- Discretion
- Character
- Honesty
- Judgment
- Unquestionable loyalty to the U.S.
And clearance holders go through background checks repeatedly to ensure they are still eligible.
One would expect that a President of The United States has all of these characteristics. A president is not required to get a background check and is granted top-secret clearance without background checks.
One thing that would disqualify anyone from getting a Security Clearance is a debt owed to another person or entity. The logic is the person might use their governmental power to aid another person or entity.