Since President Donald Trump shocked the country with hisvictory in the 2016 election, Democrats have attacked Trump with the accusation that he — or at least his campaign — colluded with the Russian government’s hacking of Democratic emails during the campaign.

And yet, as 2017 draws to a close, none of the four investigations into Russian election meddling has turned up any evidence of collusion.

Prominent Democrats have long asserted as fact that the Trump campaign colluded with Russian hacking of Democrats’ emails, despite lacking evidence to support their accusations.

“Someone in the Trump campaign organization was in on the deal. I have no doubt. Now, whether they told [Trump] or not, I don’t know. I assume they did. But there is no question about that,” then-Senate Minority Leader Harry Reid told HuffPost in December 2016. “So there is collusion there, clearly.”

“With every passing day, it gets more and more disturbing, and more and more evidence that there was collusion,” Florida Democratic Rep. Debbie Wasserman Schultz told CNN in February, without providing any evidence. “This requires, it begs, it cries out for and independent, bipartisan investigation. And Donald Trump should be the first person asking for one, but since I think he likely was part of it, it’s not surprising that hasn’t happened,” she said.

Twice-failed presidential candidate Hillary Clinton claimed in June that the Russian hackers were “guided by Americans.” She offered no evidence to support that claim.

As recently as September, California Democratic Rep. Maxine Waters guaranteed that Trump colluded with Russia. She failed to cite any evidence to support her accusation. (RELATED: Maxine Waters Pushes Trump Impeachment During Eulogy)

Bombastic media reports have fueled the unproven collusion narrative.

The infamous anti-Trump dossier, paid for by the DNC and Clinton campaign, alleged a widespread conspiracy between the Trump campaign and Russian officials.

The dossier was circulated among media outlets both before and after the election. Buzzfeed published the dossier in January, even though the outlet conceded that it had no way of verifying many of the salacious allegations within it. (RELATED: Chuck Todd To BuzzFeed Editor: ‘You Just Published Fake News’)

A New York Times report in February claimed Trump campaign aides had repeated contacts with Russian intelligence officers in the year before the election. The report cited four anonymous officials, who conceded that they hadn’t seen any evidence of collusion between the campaign and Russia’s election meddling. Former FBI Director James Comey testified in July that the NYT report was “almost entirely false.”

ABC News’ Brian Ross sent stock markets tumbling earlier this month when he falsely reported that former national security adviser Michael Flynn was prepared to testify that Trump told him to make contact with the Russians during the campaign.

Less than a week later, CNN falsely reported that Trump Jr. was given advance access to the hacked emails published by WikiLeaks. The CNN report, which relied on two anonymous sources, claimed that Trump. California Democratic Rep. Ted Lieu used the flawed report to accuse the Trump campaign of collusion. CNN has yet to explain how both anonymous sources fed the network the wrong date.

That’s not to say that the Trump campaign was devoid of scandal.

Former Trump campaign manager Paul Manafort was indicted in October on 12 counts, including conspiracy to launder money and conspiracy against the United States. However, the charges were unrelated to allegations of Trump-Russia collusion and Trump’s name didn’t appear once in the indictment records. (RELATED: Podesta Group Plays Key Role In Manafort Indictment)

Manafort, Donald Trump Jr. and Jared Kushner met with a Russian lawyer at Trump Tower in June 2016 after Trump Jr. was promised damaging information about Hillary Clinton. But nothing appears to have come from the meeting.

NBC News published what the network hyped as a “potential bombshell” in September, claiming that Manafort’s notes from the Trump Tower meeting contained a “cryptic” reference to donations in relation to the Republican National Committee (RNC). The story quickly fell apart.

As the investigations have dragged on, some Democrats have been forced to admit that they still have no evidence of collusion. (RELATED: Dianne Feinstein Says She Still Hasn’t Seen Evidence Of Collusion)

Connecticut Rep. Jim Himes, a member of the House Intelligence Committee, conceded on Thursday that the committee has little more evidence of Trump-Russia connections than the public does. “You know, I’m not sure I’ve seen a lot that the American people aren’t already aware of,” Himes said on CNN.

President Trump has steadfastly insisted that there was no collusion between his campaign and the Russians.

Again, the story that there was collusion between the Russians & Trump campaign was fabricated by Dems as an excuse for losing the election. — Donald J. Trump (@realDonaldTrump) May 12, 2017

….Also, there is NO COLLUSION! — Donald J. Trump (@realDonaldTrump) October 30, 2017

“I can only tell you that there is absolutely no collusion. Everybody knows it,” Trump told The New York Times on Thursday. “And you know who knows it better than anybody? The Democrats.”