In nominating conservative appellate court judge Brett Kavanaugh to succeed retiring Justice Anthony Kennedy on the Supreme Court, President Trump has done something exceedingly normal.

That in itself is noteworthy.

During the opening weeks of the Trump administration, it became commonplace for liberal political observers to intone gravely that the Trump presidency — including the new president's words, actions, hiring choices, policy priorities, and ethical conflicts — was "not normal." Out of this focus on the administration's divergence from the normal came a debate that continues today — about the liberal democratic "norms" that the president, his Cabinet, and staffers routinely violate, placing America's form of government itself in jeopardy.

Such worries are legitimate. But the tendency of Trump critics to treat everything the administration does and everything the president says as abnormal remains concerning. That's why, in a column written a week after Trump's inauguration, I urged critics to separate out the administration's normal, abnormal, and truly alarming words and deeds.

Judged by that standard, Monday night's announcement of Kavanaugh's nomination to the high court was an utterly normal moment. It was a Republican president seeking to fill a vacancy on the Supreme Court with a consummate conservative — with a man who might have been nominated by Ronald Reagan, George H.W. Bush, George W. Bush, John McCain, Mitt Romney, or Marco Rubio. That's why every faction on the right was at least satisfied and most were giddy as the president announced his pick from the East Room of the White House.

Yet the liberal response — from Hollywood to New York to Washington — was anything but normal. Or rather, it was the new normal of responding to everything the Trump administration does as if it were truly alarming, and perhaps even definitive proof that the imminent end of democracy is at hand. To wit:

The problem with such severe reactions isn't that that they lack any justification. Senate Majority Leader Mitch McConnell's refusal to allow hearings or a vote on Barack Obama's nominee to succeed Antonin Scalia on the Supreme Court was quite obviously abnormal — an egregious and ruthless act of norm violation that may well make it impossible for future presidents to get high court nominations approved whenever the Senate is held by the opposite party.

But the liberal response to the Kavanaugh announcement has not primarily focused on the injustice of McConnell's Republican power grab and its consequences on the number of Supreme Court slots Trump will get to fill. It has focused, instead, on the supposed extremism of Kavanaugh's legal and constitutional views. Even though Kavanaugh gives every appearance of being a mainstream conservative.

This would seem to imply that the mainstream Democratic position has arrived at the point where it considers not just President Trump's most egregious statements, behavior, and policies to be a truly alarming threat to liberal democracy in America — but longstanding, mainstream Republican positions an alarming threat, too.

That raises two significant and related dangers.

The first is the problem of crying wolf. Democrats have a long history of amping up the insults about Republican presidents and would-be presidents. Reagan's a doofus. Bush is a fascist. Romney's a racist. (Of course Republicans do the same thing with Democrats, labeling a moderate, incrementalist progressive like Barack Obama a radical and a socialist.) Now that the country confronts a president who actually does display some affinity for fascism and who actually does pursue policies rooted in racism, Democrats are left in the position of saying, "But this time we're serious!" Their case will not be strengthened by demonizing a conventional conservative jurist like Brett Kavanaugh.

Unless Democrats really do believe their own five-alarm hyperbole and now actually consider a conventional conservative jurist like Brett Kavanaugh to be a serious threat to the republic.

That is the second and far more ominous danger — whether or not it's true.

If that dire assessment of the peril posed by supposedly normal Republican ideas and goals is valid, then it means that one of the country's two parties poses something like an existential threat to our form of government — somewhat like the threat that an aggressive and potentially fatal form of cancer poses to the human body from the inside. On this view, Republicans are less a perfectly legitimate rival for power than a civic menace — a formidable enemy that needs to be decisively defeated. It's hard to see how the ordinary back-and-forth of democratic politics, with two or more parties trading or sharing power, can be allowed to continue when the prospect of the other side's political victory could precipitate the end of the system itself.

If Republicans really do pose such a threat, that's very bad. But it's also bad if Democrats merely think and act as if it's true, since it implies that they now believe that the only way to be a "good American" is to … be a Democrat. The problem with Kavanaugh, after all, isn't Trump's corruption or the gratuitous cruelty and ineptitude of his administration. The problem with Kavanaugh is the agenda of his party and its ideology going back decades.

Do Democrats really intend to suggest that Americans need to agree with them or else risk subverting American democracy as such? If so, they should be clear about it — and honest with themselves about what it implies, which is that what was formerly considered perfectly normal (the ordinary give-and-take of democratic politics) has now become a luxury the country can no longer afford.

That would signal the end of normal politics in America — and constitute a genuine crisis of American democracy. I have a hard time imagining anything more alarming than that.