Advise and Consent
In the entire US Constitution, including the 27 amendments, the term "advise and consent" only appears in Article 2, Section 2. The term appears twice. Here is the full text.
Article 2, Section 2 (second paragraph)
"He shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law: but the Congress may by Law vest the Appointment of such inferior Officers, as they think proper, in the President alone, in the Courts of Law, or in the Heads of Departments."
Advise and consent clearly calls for a two-thirds majority of the Senate to make treaties. But, the question is: does the 2/3 majority apply in general to advise and consent? The answer is not so clear cut. The use if the term "by and with" instead of just using the term "by" or "with" suggests that advise and consent might require a 2/3 majority for amdassodors, ministers and consuls ,and supreme court justices as well.
What is clear is that our founding fathers felt that treaties, ambassadors, ministers and consuls, and supreme court justices were important enough to require a check and balance from the Senate.
A case has never been brought before the courts to challenge the Senate threashold for "Advise and Consent." The Senate has felt that the threshold for Advise and consent for Supreme Court justices should be at least 60 votes. This decision is arbitrary and can be suspended at any time by the majority party. The 60 vote rule was adopted in 1975. Prior to that the rule was 2/3 (or 67 votes) in adherence to what was prescribed in the US Constitution.
In all of this what I find interesting is why the White House Chief of Staff is not subject to Senate approval. Would not the White House Chief of Staff fall under the catagory of minister and consul?