When Republicans nominate Donald J. Trump for president in Cleveland next week, it will mark the nadir of their party’s 164-year existence. To go from Lincoln to Trump is to descend from the sublime to the ridiculous.

As a progressive, I should be delighted because a Trump-led GOP should portend sweeping Democratic gains this fall. But as a citizen, I’m sickened by what Trump’s rise says about America’s democratic malaise.

Think about it. The party that saved the Union is about to hand its nomination to a vacuous and bigoted blowhard who isn’t remotely qualified to be President of the United States. He’s never been elected so much as dog catcher and gives no signs of having thought deeply about any public question. He is incapable of articulating reasoned arguments or engaging in public debate without slurring his opponents and belittling those who disagree with him.

Trump’s “ideas” are a toxic cocktail of some of the most discredited and retrograde tendencies in U.S politics—1920s-vintage nativism, Smoot-Hawley style protectionism and America First isolationism. Rather than appealing to the better angels of our nature, Trump aggravates the pathologies that are tearing our society apart—a belligerent dogmatism that is deaf to persuasion and prone to violence; a tribal politics that puts ethnic or religious identity above our common rights and duties as citizens, and a disdain for facts and evidence that don’t support one’s preferred political “narrative.”

We’re supposed to overlook this Emperor’s stark nakedness because Trump defies political correctness, gives voice to authentic grievances and “tells it like it is.” Except that he doesn’t. In fact, Trump is a chronic liar who peddles ludicrous conspiracy theories to inflame the fears and prejudices of a white working class that feels dispossessed. When called out for his falsehoods, he never mans up and admits error, but doubles down and whines that the media treats him unfairly.

Trump the narcissist is a purely subjective being who has no use for objective reality. Trump whisperers like Sen. Jeff Sessions and other GOP apologists say his outrageous claims shouldn’t be taken literally because he’s expressing deeper home truths, however inartfully. So, OK, maybe President Obama isn’t rooting for the Islamic State; what Trump is really saying is that the president isn’t hitting our enemies hard enough, and with Trumpian disregard for civilian casualties. Maybe thousands of Muslims in New Jersey didn’t really cheer the 9/11 attacks, but only Trump dares to say what conventional politicians won’t—that deep down Muslims everywhere sympathize with Islamist terrorists.

This of course is an even bigger and more destructive lie, since it not only impugns the patriotism of American Muslims but also abets the Islamist strategy of sparking a Doomsday clash between the world’s Muslims and unbelievers. But Trump is oblivious to the damage his incoherent ranting does to our country’s security or its liberal and tolerant image. He’s a showman, not a boring politician, and as long as the audience eats up his act, the show will go on.

Trump’s epic political ego trip poses an acute moral and political dilemma for Republicans. He won the nomination fair and square. Yet principled conservatives and Republicans know that he is utterly unprepared and temperamentally unfit to be president. So they face a choice between their consciences and the will of GOP primary voters. To their credit, a surprisingly large cast of the party’s leading thinkers and political figures have decided they cannot honorably back Trump and are boycotting the Convention.

Republicans who are going to Cleveland, on the other hand, will take part in an elaborately staged spectacle of make-believe. Their job will be to convince the country that Trump, for all his scary talk and deviations from party orthodoxy, is a “normal” Republican candidate. They are counting on sheer partisan animus against Hillary Clinton to overcome pervasive doubts about Trump in their own ranks—recent polls show a quarter of Republicans don’t support the presumptive nominee, and independents are split.

Nonetheless, the big story in Cleveland will be who isn’t there. The list includes the last two Republican Presidents, the party’s 2012 nominee; Mitt Romney (a leader of the “NeverTrump” movement); the host state’s governor, John Kasich; and a slew of prominent GOP Governors, Senators, Representatives; as well as corporate donors and campaign operatives. The unprecedented defection of so many key GOP leaders and supporters will make it hard for Trump to get a Convention “bounce” from a strong show of party unity.

Also striking is the revolt against Trump among the GOP commentariat. George Will, the dean of conservative columnists, has quit the party in disgust. Other Trump refuseniks include Bill Kristol of the Weekly Standard, Jonah Goldberg of the National Review, New York Times columnist Ross Douthat, Washington Post columnist Michael Gerson, Eric Erickson of Red State and a host of popular conservative talk radio hosts.

If Trump does manage to find a way to win the White House, he may have a hard time finding qualified people for key posts in his administration. Dozens of top Republican national security professionals, for example, recently declared themselves “united in our opposition to a Donald Trump presidency.” They describe Trump as “fundamentally dishonest” and say his views of American power are “wildly inconsistent and unmoored in principle.” They also chide Trump for embracing torture, calling for trade wars, inflaming anti-American sentiment in the Muslim world and in Mexico, undermining America’s alliances, and fawning over dictators like Vladimir Putin. It’s hard to imagine Democrats handing down a more searing indictment.

What Cleveland really signifies is the abject failure of the Republican Party to perform its crucial role as an intermediating institution in U.S. politics—namely, providing responsible political opposition and governing alternatives and vetting candidates to weed out crackpots, demagogues and mountebanks who have no business holding public office.

Unlike the legion of opportunists, partisan hacks and Trump enablers who will flock to Cleveland next week, the GOP dissidents are keeping faith with their party’s best principles and traditions. In them lies the best hope for Republicans’ eventual return to sanity and decency. That’s something even Democrats should wish for, because it means a stronger democracy.