Donald Trump has elevated several conspiracy tweets during his presidency. (File)

The president of the United States this weekend promoted a conspiracy theory alleging that the family of his 2016 election opponent was involved in a high-profile death that had been ruled a suicide. He was doing this for the second time.

President Donald Trump's retweeting of a Jeffrey Epstein conspiracy theory looks a whole lot like when he trafficked in a similar conspiracy about Clinton White House aide Vince Foster's suicide.

"#JeffreyEpstein had information on Bill Clinton and & now he's dead," Terrence K. Williams tweeted, appending the hashtag #ClintonBodyCount before having his tweet elevated by Trump.

This is one of the biggest conspiracy theories Trump has ever elevated, but it's hardly the only one. Below are 22 others. Trump didn't technically espouse each and every one, but he elevated all of them - no matter how specious and/or ridiculous.

1. The Clintons might be involved in Epstein's death

Trump didn't subscribe to it, but the thrust of the tweet is readily apparent. "I think the president just wants everything to be investigated," Kellyanne Conway explained this weekend. That's not what he said, though.

2. The Clintons might have been involved in Vince Foster's suicide

Trump brought up this decades-old conspiracy theory during the 2016 campaign, calling it "very serious" and the circumstances of Foster's death "very fishy." "He had intimate knowledge of what was going on," Trump said of Foster. "He knew everything that was going on, and then all of a sudden he committed suicide."

The parallels to Epstein today are readily apparent; Trump's quote closely mirrors the one from the Williams tweet. But five investigations showed no evidence of foul play.

3. Barack Obama wasn't born in the United States

This is Trump's most widely trafficked conspiracy and is arguably the one that launched his political career. Obama eventually produced his long-form birth certificate, though not even that stopped Trump from again broaching the topic in 2016. He was eventually convinced to drop it.

4. The father of Texas Sen. Ted Cruz, R, may have been involved in the Kennedy assassination

"His father was with Lee Harvey Oswald prior to Oswald's being - you know, shot. I mean, the whole thing is ridiculous," Trump said, referring to a National Enquirer story. "What is this, right prior to his being shot, and nobody even brings it up. They don't even talk about that. That was reported, and nobody talks about it."

We later found out the Enquirer did more than write stories designed to benefit Trump.

5. Joe Scarborough involved in his intern's death

Trump's Nov. 29, 2017, tweet linking Scarborough, then a Republican congressman in Florida, to "the 'unsolved mystery' that took place in Florida years ago" was clearly a reference to whispers that Scarborough had been involved in his intern's death. The case is not an unsolved mystery, though; authorities determined she lost consciousness from an abnormal heart rhythm and collapsed, striking her head.

6. The late Supreme Court justice Antonin Scalia may have been murdered

Trump told conservative talk show host Michael Savage: "I'm hearing it's a big topic. It's a horrible topic but they're saying they found the pillow on his face, which is a pretty unusual place to find a pillow." He added: "I can't give you an answer. It's just starting to come out now."

It didn't come out. Law enforcement found no evidence of foul play.

7. The "Deep State" is trying to undermine or oust him

This is one of Trump's longest-running theories, and one of its benefits is that it's very difficult (if not impossible) to disprove. That anonymous New York Times 2018 op-ed indicated there were people in the government protecting against Trump's most dangerous instincts, but there is no evidence of a large-scale, coordinated effort to undo Trump.

8. Vaccines can cause autism

"We had so many instances, people that work for me, just the other day, 2 years old, a beautiful child, went to have the vaccine and came back and a week later got a tremendous fever, got very, very sick, now is autistic," Trump said.

There is no established link between vaccines and autism, and people refusing to get their kids vaccinated because of such concerns are causing things like measles outbreaks.

9. The death toll from Hurricane Maria was inflated

Trump tweeted, "3000 people did not die in the two hurricanes that hit Puerto Rico," adding that people who died of old age were simply added to the death toll, and he blamed Democrats for inflating it.

Neither of these claims hold up. The death toll did rise in studies thanks to longer-term effects of the disaster. But those studies controlled for natural deaths, and they weren't performed by Democrats.

10. Muslims are attempting to install sharia law in the United States

"Anyone who believes sharia law supplants American law will not be given an immigrant visa," Trump said in August 2016. He added in a TV interview: "They don't want laws that we have. They want sharia law."

This is a well-trafficked anti-Muslim conspiracy theory, with some red states and locales even passing laws to prevent sharia law from taking hold.

11. Thousands of Muslims celebrated in the streets in 9/11

"I watched when the World Trade Center came tumbling down," Trump said. "And I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down. Thousands of people were cheering." He added later: "It did happen. I saw it . . . It was on television. I saw it."

There may have been isolated incidents, but nothing on the scale Trump was talking about.

12. Cruz wasn't eligible to be president because he was born in Canada

"I'd hate to see something like that get in his way," Trump said. "But a lot of people are talking about it, and I know that even some states are looking at it very strongly, the fact that he was born in Canada and he has had a double passport."

Cruz was born to an American citizen in Canada, and while it's never been tested in the courts, legal experts generally agree that satisfies the Constitution's requirement that you be a "natural born citizen."

13. Marco Rubio wasn't eligible, either

This is even more baseless than the Cruz one. Rubio was born in the United States.

14. 3 to 5 million illegal votes in the 2016 election - but none for Trump

Trump has regularly claimed as many as 3 to 5 million illegal votes, which is coincidentally enough to cover his nearly 3 million-vote loss in the 2016 popular vote. And he said none of the allegedly illegal votes were for him. "None of 'em come to me," he said. "They would all be for the other side."

Trump later established an election integrity commission headed by Kris Kobach. It found nothing even remotely amounting to this level of fraud before disbanding.

15. Obama wiretapped Trump Tower

Trump floated this idea before it was shown that the FBI wiretapped a former Trump campaign adviser, Carter Page, and that it also wiretapped his former campaign chairman, Paul Manafort. But neither was "Obama" nor were they "Trump Tower." There is still no evidence that Trump Tower was wiretapped.

16. Global warming is a hoax perpetrated by the Chinese

On Nov. 6, 2012, Trump tweeted: "The concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive."

The vast, vast majority of scientists say climate change is real and is caused by man. Trump later suggested his tweet was a joke.

17. A man who charged the stage at his rally had Islamic State ties

The video Trump tweeted on March 12, 2016, was dubious at best, and no U.S. government agency has tied the man to the Islamic State terrorist group. When pressed by Chuck Todd, Trump tempered his allegation but didn't disown it. "He was playing Arabic music. He was dragging the flag along the ground, and he had internet chatter with ISIS and about ISIS. So I don't know if he was or not," Trump said.

He added: "What do I know about it? All I know is what's on the internet."

18. The "white genocide" of South African farmers

As Vox has written, there is no evidence of the "large scale killing of farmers" in South Africa. White nationalists have claimed there is and that it amounts to a "white genocide."

19. It might not be his voice on the Access Hollywood tape

"We don't think that was my voice," Trump reportedly told a GOP senator he was imploring to investigate, according to the New York Times. Trump had previously apologized for the lewd recording.

20. Gen. John Pershing executed Muslim terrorists with blood-tipped bullets

"He caught 50 terrorists who did tremendous damage and killed many people. And he took the 50 terrorists, and he took 50 men and he dipped 50 bullets in pigs' blood," Trump said. "And he had his men load his rifles, and he lined up the 50 people, and they shot 49 of those people. And the 50th person, he said: You go back to your people, and you tell them what happened. And for 25 years, there wasn't a problem. Okay? Twenty-five years, there wasn't a problem."

This is a baseless anti-Muslim story that has circulated for years on the internet.

21. Wind farms cause cancer

"If you have a windmill anywhere near your house, congratulations, your house just went down 75 percent in value," he said. "And they say the noise causes cancer. You tell me that one, okay?"

Whoever says that has no evidence to support it.

22. The danger of asbestos is a "con" pushed by the mafia

"One of the great cons is asbestos," Trump told New York magazine in 1992. "There's nothing wrong except the mob has a strong lobby in Albany because they have the dumps and control the truck."

The World Health Organization says 100,000 people die annually from asbestos exposure.

23. A Saudi prince co-owns Fox News

Before Trump viewed the Saudis as important business partners, they were nefarious alleged Fox News co-owners. But the photo he tweeted was fake and the prince, billionaire Prince Alwaleed bin Talal, was not a Fox News "co-owner." He instead owned a small shared of 21st Century Fox through his investment company.