On October 2, former President Donald Trump filed this brief in Castro v Aguilar, 2:23cv-1387. This is the case in which John Anthony Castro has sued the Nevada Secretary of State to keep Trump off the Nevada Republican primary ballot.
The brief makes many points, but the most interesting part of the brief explains why the Fourteenth Amendment, section 3, does not apply to presidential candidates. Section 3 mentions congressional candidates, and candidates for presidential elector, but no other specific offices. It goes on to include “any office, civil or military, under the United States, or under any State”. Many readers believe it is obvious that “president” is an “office…under the United States”, but the brief does a good job of rebutting that presumption.
The brief points out that presidents do not take an oath to “support” the Constitution. Instead, the Constitution says presidents take an oath to “preserve, protect and defend” the Constitution. But every other federal officer takes an oath to “support the Constitution”, and the 14th amendment, section three, only applies to people who had previously taken an oath to “support” the Constitution.