Civic Lesson: Filibuster? Cloture? Why does the minority hold so much power? Our Senate is really full of Swamp Monsters!

This is almost correct. If you look at Article 2 s.3 there are no actual Senate rules. This reasonably means that a simple majority was the intention of the framers. This being said the Senate is allowed to make it's own rules and still be constitutional. Recall that that as mentioned before there is no guidance given on what constitutes an affirmative vote.

It does not take a 2/3rds majority to change a senate rule. This is why the so called "Nuclear option" when confirming Gorsuch was such a powerful tool. While traditionally according to the Senate rules 60 votes were required to confirm an individual to a cabinet office, judgeship, general officer position etc. This however is merely a rule and not in the constitution. To change a rule only takes a simple majority because that is implied by the language of the constitution. This can be seen in Article 2 s. 2 with the words "advice and consent of the senate", again there is no vote threshold explicitly mentioned implying a simple majority.

/r/The_Donald Thread