The 80 year myth circulated by Senate Majority Leader McConnell, Senate Judiciary Chairman Grassley and every Presidential GOP candidate is easily dispensed with:
Contrary to the GOP Senate Majority Leader's claims that the Senate has not confirmed a Supreme Court Justice during an election year in over 80 years, that same person confirmed the currently serving Justice Kennedy in an election year (1988) and Justice Murphy was confirmed in 1940.
In the Supreme Court's history, 21 people have been nominated in an election year.
However, their obstruction based on fallacy is worse than that.
In only 4 years was someone appointed but not confirmed to the Supreme Court in an election year.
Those were all special cases.
In every case, the Senate was controlled by the same party as the President.
So an opposition party Senate has NEVER blocked a Supreme Court nominee in an election year. Not once in the 228 year history of the world's longest democratic constitution.
In all the 4 years above, the President was unpopular within his own party.
In 1968, the former Senate Majority Leader, President Johnson was at war with a large faction of his party. He was so unpopular as president that he decided he couldn't win his own party's nomination and withdrew. Sitting Supreme Court Justice Abe Fortas was nominated to take over for retiring Chief Justice Warren. Fortas had angered this faction of the president's party both because of his close association with he president and his own dubious acts. More details are here.
In 1852, the President was so unpopular he was not nominated for reelection by his own party. Like the case in 1844 the President had only become President by being VP when the President died and failed to win an election in his own right.
By 1844, the President had been thrown out of his own party and rejected all 7 of his nominations while the President continued the spat by renominating already rejected nominees multiple times. More details on this are here.
In 1824, President John Quincy Adams was chosen as part of the Corrupt Bargain by the House of Representatives despite the President losing to Andrew Jackson by 11% in the popular vote (no candidate had reached 50%). Both were members of the same party. The corrupt bargain poisoned his administration. A couple weeks after Andrew Jackson beat him in the 1828 election, John Quincy Adams nominated a Supreme Court justice, who was not confirmed and 22 days later Andrew Jackson nominated his own candidate. More details are here