But those purportedly noble and principled Republicans don't need Trump to undermine our democratic institutions. They are already doing so themselves by thwarting a sitting president's efforts to appoint a well-qualified candidate to the United States Supreme Court -- a nominee that they had previously praised -- for no other reason than it would likely alter the ideological balance on the Court. And John McCain has now made explicit what has been a poorly kept secret -- that the Republicans will continue to oppose whatever nominee the next Democratic president selects: "I promise you that we will be united against any Supreme Court nominee that Hillary Clinton, if she were president, would put up. I promise you."
This is a stunning admission. Presidents have always been given deference in filling Supreme Court vacancies, as Jonathan Chait explained: while "senators might object to a particular nominee on the basis of ideological extremism or lack of qualifications,  the president’s general right to appoint a member of his judicial team was considered sacrosanct.”
But, as I wrote back in February, after the death of Justice Scalia when Republicans began crafting excuses for why they would not consider a replacement chosen by President Obama, "Republicans Will Not Release Their Stranglehold On The Supreme Court (Ever)." That is because Republicans rely on a conservative Supreme Court to obstruct liberal initiatives and ensure that their own policy positions are enacted or upheld -- such as allowing unfettered campaign contributions, limiting voting rights, gutting environmental regulations and protecting Wall Street. Maintaining a right wing court is also a critical rallying point for social conservatives who make up their base, and who often vote Republicans not out of economic self-interest but in the hope of limiting restrictions on the Second Amendment and overturning Roe v. Wade.
Importantly, the Republican's Supreme Court obstruction is not another case of both sides do it. Republicans like to argue that it was the Democratic Party that started politicizing Supreme Court nominations when they defeated Reagan's nomination of Robert Bork in 1987. But Bork was no mere conservative. He was a radical jurist whose views on the federal role in protecting civil rights, voting rights and reproductive rights were quite far outside the mainstream. Bork's nomination was not filibustered; he was given a full, if incredibly contentious, confirmation hearing, after which six Republicans voted with the Democrats to reject him. Notably, Reagan's subsequent appointees -- Kennedy (who was nominated after Bork's defeat) and Scalia -- were confirmed, as were the extremely conservative nominations of the two presidents Bush.
As a result, Republicans have had a majority on the Supreme Court since the Nixon Administration, and have truly come to believe that this is how it must always be. As McCain strongly implied, they think that only a Republican president should be able to make Supreme Court appointments. But in a functioning democracy, one party does not get to keep a branch of government for themselves.
The only way to stop them is for Democrats to not only win the presidency but to take back the Senate -- flipping five states (or four if they can hold Nevada). With a Senate majority, Democrats can take away the Republican filibuster if they continue to abuse it by refusing to permit up-or-down votes on the president's choices to the Supreme Court (and the lower federal courts).
Trump is an ignorant blowhard who either doesn't understand or doesn't care about democratic principles. Luckily, he will never have his tiny little hands on the levers of power. But we still need to worry about the Party that nominated him.