Donald Trump is a damaged person. And he is leading a morally corrupted political party.

I’m not speaking about Trump’s presidential campaign, but rather of Trump personally. How else can one explain his response, over the past several days, to Khizr Khan and his wife, Ghazala Khan? The Khans appeared at the Democratic National Convention last week to speak about their son, who was killed serving in Iraq, and to lambaste Trump for his disrespect not just for Muslims, but for the very Constitution he would pledge to defend if he were to be elected president.

It certainly would not be easy to answer such criticism, but Trump’s response has nonetheless been astounding. He’s accused Khizr Khan of “viciously attacking’’ him. He said that he’s sacrificed for his country, by creating jobs through his business. And he intimated that Ghazala Khan did not speak at the DNC because she was perhaps “not allowed’’ to talk — a racist charge meant to suggest that, because she is Muslim, she is subservient to her husband. These are not the actions of a rational person.

But if this election has proved anything, it is that Donald Trump is a thin-skinned, egotistical person with a striking lack of empathy and compassion. It doesn’t seem like a stretch to suggest that Trump is emotionally incapable of moderating his behavior.

But how does one explain why so many Republican leaders continue to support and endorse his presidential bid?

Many of them, like Speaker of the House Paul Ryan, Senate majority leader Mitch McConnell, and Senator John McCain have offered kind words for the Khans and criticized Trump’s Muslim ban. In the case of McCain, he directly criticized Trump. By doing so they’ve made clear that they understand why his words are so wrong.

Yet each of them is still on record having endorsed Trump’s bid to be the next president of the United States. This singular fact makes their support for the Khans as negligible as Trump’s personal capacity for empathy.

It shows that they know better and they understand the moral choice they are making by supporting Trump. Yet they continue to do it.

I’m perhaps being generous. It’s not as if we’ve learned something new about Trump this weekend. For 13 months, we’ve seen him violate the most basic democratic norms and values that we hold dear in this country. He’s spoken of religious tests. He’s scapegoated minorities and in particular illegal immigrants, whom he calls rapists and murderers. He’s made misogynist statements, delivered personal attacks on his political rivals, and mocked a disabled reporter. He’s talked about using the Department of Justice to go after newspaper owners who displease him and encouraged foreign governments to investigate Hillary Clinton.

And yet the overwhelming majority of Republican officeholders and political leaders have made clear that they still believe he is the best candidate for president and that electing Hillary Clinton would be a far worse disaster for America.

I don’t doubt that are some Republican leaders who genuinely support Trump. But for many there is a simpler explanation for why they’ve made this decision: politics. They have concluded that if they hope to have a viable future in the Republican Party — or in the case of McCain, win reelection in the fall — they cannot get on the wrong side of Republican rank-and-file voters. So they endorse or announce their support for Trump, but they skipped the RNC or won’t appear with him at political events. Many undoubtedly want him to lose, but they don’t want to be on record having gone against GOP voters.

They have betrayed not only their own supporters, but also the country they regularly claim to revere. The very presence of Trump on the top of the RNC ticket, and the fetid rhetoric that spews forth from him, coarsens America and undermines our democracy. Trump’s candidacy is emboldening and empowering bullies, racists, xenophobes, anti-Semites, and white supremacists. It is frightening Hispanics, Muslims, and other minority groups who fear what might happen to them if Trump wins. It will take years to wash away the damage that he has already done.

This is the Trump Effect, and Paul Ryan, Mitch McConnell, John McCain, Marco Rubio, Kelly Ayotte, Chris Christie, Mike Pence, and countless other Republicans have fed it with their political cowardice.

I remain confident that Trump will lose this election. But what about the craven politicians who did and said nothing to stop his rise? What about the Republican leaders who incessantly talk about their undying devotion to the Constitution, to individual liberty, to democracy, to US leadership at home and abroad, and to basic American values, but through their actions have systematically undermined every one of these national attributes by endorsing Trump?

They will take that decision to their graves.

Nothing they do or say can excuse it away.

And no American who loves this country should ever allow them to forget what they’ve done.

Michael A. Cohen’s column appears regularly in the Globe. Follow him on Twitter @speechboy71.