-- Chief Justice John Marshall was appointed in 1801 -- not an election year ... but only because the election was already over, and John Adams had lost! And lost Congress! Lame duck squared! But constitutionally still in office. Meanwhile they were adding new judgeships for Adams to appoint at the last minute (Midnight Judges), and subtracting judges from the Supreme Court such that Jefferson wouldn't be able to pack it with his own people.
-- For a time, Marshall was technically both Chief Justice and Secretary of State!
-- And he went on to serve 35 years! And set the tone for the Judicial Branch to this day (Marbury v. Madison -- a case in which he had about six dozen conflicts of interest).
-- Yes, yes, yes the other party screamed. They even passed a law delaying the Supreme Court's session such that in effect the court didn't even convene for a year and a half.
-- The Constitution ensured lifetime appointments, so the only way for Jefferson's crowd to expel the Adams appointees would be impeachment. They tried this with a bald-faced political impeachment of Samuel Chase, one of the signers of the Declaration of Independence. The Senate declined to remove him from office, setting the precedent that judges not be removed just for their opinions.
So big political fights over the nature of the judiciary is nothing new. Parties using their constitutional prerogatives such as they are to ram things through and/or delay-delay-delay also nothing new.
Hypocrisy dependent on whether your party is doing the ramming through or the delaying (and which serves your interest at the time) also nothing new.
Parties with the power to ram through, ram through. Parties with the power to delay, delay.
Generally, though, the notion that highly-qualified individuals would be disqualified simply on the basis of opinions disfavored by the majority party did not break through until 1987 with Robert Bork. And that was largely due to the idea that Bork would threaten Roe in a way that an Anthony Kennedy ultimately would not (which turned out to be correct).
Of course, now we are told that "Bork-ing" is only a one-way street. It is only permissible against appointees who might threaten Roe (and, presumably, now the Obergefell marriage case as well -- determined, as it were, by the Justice appointed instead of Bork).
The President absolutely has the power to nominate, and can't be prevented from doing so. The President has no authority to force the Senate to bring any matter up for a vote, and no nominee can take office without both.
Both sides will spin the debate, but there are only about 3-4 GOP senators in tough races, and really the only one who might be seriously hurt by delaying a vote (Kirk of Illinois) is likely to lose anyway.
Regardless, if it were to come to that, I think the GOP would sacrifice a couple of Senate seats to prevent a guaranteed fifth vote for the left side of the Court.