Donald Trump’s recent attacks on the federal judge hearing the fraud lawsuit against his for-profit Trump University are despicable and dangerous. Fortunately, Trump’s statements that U.S. District Court Judge Gonzalo Curiel couldn’t preside over his case fairly because he is “Mexican”—Judge Curiel was, in fact, born in the United States and raised in Indiana—have been decried even by some of his fellow Republicans as “very disturbing,” “inexcusable,” “flat out wrong,” and “the textbook definition of a racist comment.“ Trump, however, has appeared undeterred, doubling down on his views of the type of person who can serve on the bench by saying it is “possible“ that a judge who is Muslim might not be able to serve as the impartial judge our justice system requires.

This so deeply wrong it is beyond question. Time after time, the courts have made clear that a judge’s impartiality cannot be called into question because of his race, ethnicity, or religion. But Trump is not the only one placing the judiciary in harm’s way through personal and political attacks—he is just the loudest voice in a recent uptick of assaults on the integrity of the Nation’s courts.

For example, the Republican Senators refusing to consider President Obama’s Supreme Court nominee are also guilty of threatening our judicial branch. Within hours of the news that Justice Antonin Scalia had passed away, Republican Senate leader Mitch McConnell declared that he would not consider any nominee put forth by President Obama—despite the fact that the Constitution makes clear that the President has the duty to put forth such a nominee, election year or no. The Republican-led Senate, by refusing to even hold a vote on the unquestionably qualified nomination of Judge Garland, has done its best to try to drag the judicial branch down into the political mire. As Senator Patrick Leahy explained, while Trump’s comments are abhorrent, the refusal to give a public hearing and vote to Judge Merrick Garland is the “attack on our independent judicial system that more Americans need to understand.”

None other than the current—conservative—Chief Justice of the United States, John Roberts, has explained why such an attack is so dangerous: “When you have a sharply political, divisive hearing process, it increases the danger that whoever comes out of it will be viewed in those terms….If the Democrats and Republicans have been fighting so fiercely about whether you’re going to be confirmed, it’s natural for some member of the public to think, well, you must be identified in a particular way as a result of that process.” But, Chief Justice Roberts made clear, “We don’t work as Democrats or Republicans, and I think it’s a very unfortunate impression the public might get from the confirmation process.”

Unfortunately, Trump’s claims about who can be “fair” to him in a court of law—and some Republican Senators’ idea of who is an acceptable Supreme Court Justice—directly implicate the Chief Justice’s concerns: they suggest that only a judge like me, who supports me, who comes from my party should serve on the bench; only a decision from that sort of judge will be legitimate.

This trend of personal and political attacks on judges and the courts would horrify our Nation’s Founders. When the Constitution was being drafted and debated, the Framers explained time and again that the courts would serve as a crucial check on the political branches of government. Recognizing that the courts would be needed to stand up to the powerful, whether that power was wielded by elected leaders or popular majorities, the Framers of our Constitution understood that the protections of our Founding Charter “can be preserved in practice no other way than through the courts of justice, whose duty it must be to declare all acts contrary to the manifest tenor of the Constitution void.” As Alexander Hamilton declared, “laws are a dead letter without courts.”

Those who lack the megaphone of wealth and power find their voice when they stand before the court and invoke its protection. By attacking the integrity of judges based on their color or creed, Trump is trying to bully the officials and institutions our Founders envisioned as the bulwark against such intimidation and lawlessness. But we should find equally unacceptable attempts to use the courts—especially the Supreme Court, which our Founders designed to be the “keystone of the arch” of our judicial system—as a political football. So long as Republican Senators insist on holding a vacant seat open on the Supreme Court for no reason other than pure politics, they are threatening real harm to our system of justice.