It's not guilt by association. Trump is choosing to cozy up to far-right conspiracy theorists.

This is an adapted excerpt from the Sept. 12 episode of "All In with Chris Hayes."

On Wednesday, the United States marked 23 years since the Sept. 11 attacks that killed almost 3,000 people. To mark that solemn anniversary, Donald Trump attended a remembrance ceremony in lower Manhattan and, as his guest, the former president brought along Laura Loomer, a conspiracy theorist who has called 9/11 an “inside job.”

Loomer joined Trump and his running mate, JD Vance, as they took photos with firefighters. It’s a scene you can’t make up — you wouldn’t want to. It’s absolutely heinous. But it’s also, sadly, unsurprising.

For almost a decade now, Trump has used his political platform to channel the worst, most vile, discredited and disgusting rhetoric and ideas and people, and mainstream them into American culture.

From re-posting Nazi trolls during his 2016 campaign to defending “some of” the torch-carrying, "Sieg Heil" saluting, neo-Nazis as “very fine people” in Charlottesville while he was president to whipping up violent far-right gangs and extremist militias such as the Proud Boys and the Oath Keepers. Trump has also dined with neo-Nazis, courted Holocaust deniers and endorsed conspiracy theorists. 

In fact, on Thursday, NPR reported that a Nazi sympathizer, who served three years in prison for storming the Capitol on Jan. 6, was an honored guest at two different events at Trump’s Bedminster golf resort. At one of those events, a fundraiser for the Jan. 6 rioters, Trump addressed the crowd by video, saying, “All of the people there, you’re amazing patriots. Have a great time at Bedminster.”

Trump has also forged a bond with billionaire troll Elon Musk, saying that if he’s elected, he’ll put Musk in charge of a “government efficiency” commission. This week, when Taylor Swift endorsed Trump’s opponent, Musk responded by posting the creepiest, truly unsettling, sexist taunt to the pop star on the social media platform he owns.

Trump cleaves to some of the absolute worst, most dangerous people and if he becomes president again, it will probably be even worse. 

Laura Loomer is Exhibit A. The two seem to be inseparable lately. In addition to being his 9/11 guest, she accompanied Trump to Tuesday’s debate in Philadelphia. She’s been seen with him at his Bedminster club and her name has been on Trump’s lips for much of this year.

Many Republicans are now expressing concern to reporters about Loomer’s closeness to Trump. “Everyone who works for him thinks she’s a liability,” one Trump ally said. Others have told reporters that Loomer has contributed to some of the most outrageous conspiracy theories that Trump is now using as campaign fodder.

Even in the very large pantheon of Trump sycophants, Loomer is a chilling figure. She has a long history of racist and Islamophobic comments. She first gained notoriety for chaining herself to the door of a Twitter office in New York, to protest against the website for banning her after she spread false conspiracy theories about multiple mass shootings. Before that ban, Loomer also tweeted hateful bile about immigrants. She responded to a news story about thousands of migrants dying while trying to cross the Mediterranean to safety by expressing a desire that more die soon.

After Musk bought Twitter, Loomer was reinstated on the platform. That’s where she called 9/11 an inside job, arguing that Donald Rumsfeld helped stage it to take over the national security bureaucracy. Twitter is also where, this past summer, Loomer made shockingly disparaging comments about Vice President Kamala Harris. Around that time, as Trump was praising her at rallies, Loomer also called for the death of Trump’s perceived political enemies.

In advance of the debate last weekend, Loomer tweeted “If Kamala Harris wins, the White House will smell like curry.” A jab at Harris’ Indian heritage that is so racist, it got called out by a fellow Republican who said, “This is appalling and extremely racist. It does not represent who we are as Republicans or MAGA. This does not represent President Trump.”

And that Republican … was Marjorie Taylor Greene. Yes, the Jewish space lasers lady.

In truth, Loomer is just deploying all of the same rhetorical tactics that Greene and others in the MAGA movement, including Trump and Vance, have used: the bigotry, the deflections, the calls to “protect free speech!” 

You’ve heard it again this week, as Republicans continue to spread an incredibly vile and dangerous lie — falsely accusing Haitian immigrants in Springfield, Ohio, of stealing and eating house pets. All week, city officials have said it’s a lie. It didn’t happen. On Thursday, the Springfield City Hall and other municipal facilities were shut down after receiving a bomb threat. 

On Friday, two schools in the city were evacuated and another closed for the day because of “information received from the Springfield Police Division.” Haitian families in that community are now reportedly keeping their kids home from school and staying home out of fear of racist violence. One woman, who said her car had its windows broken and acid thrown on it, told a reporter, “I’m going to have to move because this area is no longer good for me. I can’t even leave my house to go to Walmart. I’m anxious and scared.” 

This is the fallout from the racist lies Vance and Trump continue to push.

The false rumor started online and spread like wildfire late last month after a speaker at a Springfield City Commission meeting warned that “crime and savagery will only increase with every Haitian you bring in.” That man turned out to be a leader of a neo-Nazi group calling itself Blood Tribe. He was immediately kicked out of the meeting for his racist rant. But now, his talking points are the talking points of a presidential campaign.

Republicans understand that the lies they’re perpetuating about immigrants lead to violence against immigrants. You know how I know? Because I heard it from a close confidant of Trump … Laura Loomer:

“Every damn day, we see another story about illegal aliens going to the Ritz Carlton, illegal aliens getting free flights, illegal aliens getting free clothes and free cellphones — and someone’s going to snap … It’s going to happen and you know what? I’m not going to care when it happens. You know why? Because there’s only so much people can take,” Loomer said on Rumble back in March. 

It all reminds me of what President Joe Biden has repeatedly said about his decision to run against Trump in 2020. Biden said he wanted to run because of Trump’s defense of neo-Nazis in Charlottesville — the “very fine people.” Biden said, correctly, that he was in a battle for the soul of the nation.

Biden may be out of the running but that battle continues today. Trump has always been an organizing and rallying force for some of the absolute worst people in the country: the people who march with torches, bash cops’ brains in and carry a confederate flag in the Capitol. The people who throw around vile racist slanders against immigrants and Harris. 

It’s not just guilt by association, Trump is choosing to empower people like Loomer and they're exactly the sorts of people who will enjoy greater power in a second Trump term. Of all the reasons to prevent him from winning another term, that might be the most important.