We get worked up about a lot of silly stuff in presidential campaigns, micro-controversies driven by faux outrage that are inevitably forgotten in a couple of days once the next micro-controversy comes along. On first glance, that is what the kerfuffle over Donald Trump’s latest Twitter hijinks — once again, passing on something from white supremacists — looks like. After all, should we really care what is in Trump’s Twitter feed, when we are talking about our country’s future? The answer is that we should care, but it’s not about the tweet. The tweet isn’t the problem, the tweet is the result of the problem.

In case you have not heard, here is what we’re talking about, from The Post’s David Weigel:

“It was so close to the message that Republicans say they want from Donald Trump: a tweet describing Hillary Clinton as ‘crooked’ and the ‘most corrupt candidate ever’” on the morning that the likely Democratic presidential nominee met with the FBI.

“But the image that Trump chose to illustrate his point, which portrayed a red Star of David shape slapped on to a bed of $100 bills, had origins in the online white-supremacist movement. For at least the fifth time, Trump’s Twitter account had shared a meme from the racist ‘alt-right’ and offered no explanation why.”

The Trump campaign later did some quick photoshopping, replacing the Star of David with a circle. But as Anthony Smith, of mic.com, discovered, the image originated on an online forum where unapologetic racists and white supremacists gather to bathe in each other’s vomitous hate.

I assume that, as with the other times that Trump has retweeted something from the alt-right, he was unaware of its origin; one of his followers tweeted it to him, he liked what he saw, and he passed it on.

It is just a tweet, and in and of itself it does not make Trump a racist or an anti-Semite. It doesn’t even make the top 20 most bigoted things that Trump has said or done in this campaign. But it should leave Republicans with even more questions about how to square the ideals they claim to hold with the man their party has chosen to lead the United States of America.

We have to understand that this is about both rhetoric and substance. There’s a stylistic element, the way Trump gives people permission to let their ugliest feelings and beliefs out for display under the guise of not being “politically correct”.

But there are also meaningful consequences for the course we would take in the future. Trump tells voters to hate and to fear people who do not look like them, but he also tells them to take action. Just the other day, he told a crowd that “we are going to be so tough, we are going to be so smart and so vigilant, and we’re going to get it so that people turn in people when they know there’s something going on”, complaining that too many people are worried about being accused of racial profiling to turn in their neighbours. So if you spot a Muslim, go ahead and dial 911. When a woman at one of his events suggested that we “get rid of all these heebeejabis they wear at TSA; I’ve seen them myself”, Trump responded: “We are looking at that. We’re looking at a lot of things.”

I’ll bet.

By this time, we have all become accustomed to this pas de deux of hate between Trump and his supporters. When he says that a Latino judge from Indiana cannot do his job because “he’s a Mexican”, we shake our heads. When he tells an apocryphal story about a general executing Muslim prisoners with bullets dipped in pig’s blood as a lesson in how America ought to act, our shock does not last more than a day. When he laments that Islamic State can behead people while we are restrained by our laws and morality, saying “they probably think we’re weak” and “you have to fight fire with fire”, we barely take notice. When he weds his support of bigoted policies such as bans on Muslims to a fetishisation of violence and brutality, promising to use torture and telling his supporters how he would love to beat up the protesters who come to his rallies — “I’d like to punch him in the face, I’ll tell ya” — we predict that any day now he will “pivot” and start acting “presidential”. And we forget that not long ago the man now leading the GOP made himself into America’s most prominent birther, going on every TV show he could to claim that President Obama might be the beneficiary of a decades-long conspiracy to conceal that he was actually born in Kenya. If you are wondering whether that is just stupid and crazy, or if it is inherently racist, let me clear it up for you: yes, it is racist.

In my analysis of American politics, I try as often as possible to put myself in the shoes of people I disagree with, to take their arguments seriously and to understand where they are coming from, even when I’m convinced they are wrong. And I’ve argued that there are perfectly rational reasons a committed Republican would grit their teeth and support Trump, even if they found him to be an ignoramus and a buffoon.

But there comes a point at which one would have to say: even if a Trump presidency would deliver much more of what I would want out of government policy, from the Supreme Court to domestic policy to foreign policy, I simply cannot be a part of this. Donald Trump’s appeal to Americans is so rancid, so toxic, so foul that my conscience will not allow me to stand behind him, even with the occasional protest that I don’t agree with the latest vile thing he said, or the insistence that my fellow Republicans and I will do our best to restrain his ugliest impulses.

You may respond: easy for you to say. Would I be saying that if I had something to lose, if we were talking about some liberal version of Trump who had secured the Democratic nomination? If it meant handing the Supreme Court over to conservatives, and repealing the Affordable Care Act for real, and privatising Medicare, and dismantling environmental and worker protections, and so many other things that would pain me?

I cannot say for sure, partly because I cannot fathom who a liberal version of Trump would be or what that person’s equally noxious campaign would look like. The closest analogy in my lifetime to this situation is the Lewinsky scandal, where Democrats argued that although Bill Clinton’s behaviour in having an affair with a 22-year-old White House staffer was repugnant, it was not an impeachable offence and could be separated from his performance as President.

But the difference then was that it could be separated from his performance as President. Clinton was not trying to persuade the country to embrace adultery, or counting on fellow adulterers to put him in office, or promising to institute a government programme of adultery.

Donald Trump is not hoping that he can keep his bigotry a secret; he’s running on it and promising to enshrine it in federal government policy. He may not be responsible for all the things his fans say, and you may even excuse him for passing on some of their hate by mistake.

What he is responsible for is all the reasons those people became his fans in the first place. It isn’t because of economic anxiety, or because he is an outsider, or because he tells it like it is. It’s because Donald Trump appeals directly to the worst in us, and the worst of us.

And every Republican who stands with him, no matter how uncomfortable it makes them or how much they wish he would change, will have that stench on them for a long time to come.

•Paul Waldman is a contributor to The Plum Line blog, and a senior writer at The American Prospect