Political parties, the president cabinet, and national nominating conventions are considered examples of

The unwritten constitution.

Explanation:

The unwritten constitution refers to the rules followed by our government that are acknowledged as a vital component of the system but they are not really in the Constitution. These are practices that have been done in a certain way for so long that many people think they are laws.

For example, the formation of a cabinet to advise the president is a precedent set by George Washington, neither required nor suggested by the Constitution.

lincoln declared that slavery should not be allowed to spread into the new states, and of course this angered the south at the time.

oil! is what i am assuming