Sometimes, taking a step back from the day to day horror of Republican politics let's you put together a couple of disparate puzzle pieces. Case in point: What does the GOP gain from backing a losing and extraordinarily toxic presidential campaign? And how does this tie into the doomed Republican effort to keep the 9th seat on the Supreme Court empty?
To answer that, you need to put yourself in the mindset of a Republican. You are going to lose the White House. Even with all of the phony outrage over Hillary's emails, she's going to beat Trump. You're almost certainly going to lose the Senate as well and that means you've lost the Supreme Court. There is simply no chance that Democrats will let you filibuster every nomination for the next 4 to 8 years.
So why tie yourself to the albatross that is Donald Trump? And why not just allow Obama to appoint the very moderate Merrick Garland? He's got to be better than anyone that Hillary is going to appoint with the backing of a Democratically controlled Senate.
The answer is deceptively simple when you look at it from a distance: Pure long term strategy. Republicans are taking a short term hit to delay their inevitable demise. It's the kind of strategic thinking we rarely see from a party more accustomed to lurching from one self-inflicted crises to the next.
The reality is that a lot of voters are holding their noses to vote for Trump because they fear the Court shifting to the left for a generation (or two). This is why Republicans are making so much noise about keeping Scalia's seat empty, guaranteeing a far more liberal Justice on the bench after Hillary wins. If they were to confirm Garland, there would be no reason for moderate Republican voters to show up on election day to vote for someone they hate. And that brings us to the bigger picture: Holding on to the House.
The only thing keeping Republicans from being reduced to a regional party is their extreme gerrymandering. But if Trump were to lose in a massive double digit landslide, Democrats could easily take the House. Even a "small" 6 point lead gives them a real shot.
That would give Democrats the chance to pass laws making partisan gerrymandering and Voter ID illegal and to reinstate the Voting Rights Act. With Democrats in control of the White House, the Supreme Court and all of Congress, Republicans would be helpless to block anything. This would effectively doom the Republican Party for decades.
With all of this in mind, the GOP's curious reluctance to distance themselves from Trump and their renewed attacks on the Supreme Court make perfect sense. It's a poisonous symbiosis and it's the only way for Republicans to hold on to power long enough for some seismic event like 9/11 to propel them back into power. It's a twisted hope but it's all they've got left.