Well here is more after refreshing my memory of reading Article 2 Section 2 of the Constitution about Exec Powers.
The president has the power to nominate supreme court justices. It is also stated that "The President shall have Power to fill up all Vacancies that may happen during the Recess of the Senate" Now back then recesses might be a month or two long so a strict reading of the Constitution should agree with a rather quick process to fill a scotus vacancy. I dont think anyone can argue that. There is no logical way on Earth that it would or should take 9 months for the Senate to interview and confirm a scotus nominee.
And just before the recess nomination part of Article Section 2 it states that He being the president "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,"
So the US Constitution states that the Senate's job is to advise and consent on the nominations of the president of people to the Supreme Court. So to do that job the Senate has to perform some sort of advise and consent as in voting for the nominee. Mitch McConnell held back and did neither of those things with the help of Grassley who was Judiciary Comm Chair. It was a terrible stain on them but of course they do not care that they evaded their duties.
But Mitch M stonewalled the process and the process of the rules of the Senate are they are supposed to confirm or deny the appointment, once again not doing their job and even blocking procedure.