Donald Trump has blamed a wide range of groups for the frequent and disruptive protests at his rallies, pointing the finger at the Bernie Sanders campaign, the remnants of the radical Weather Underground – even ISIS – and suggesting high-powered forces are behind the counter-Trump factions.

The reality, though, is a bit more nuanced than that.

So far, the protests largely have been driven by a hodgepodge of liberal groups and activists. Sanders supporters, MoveOn.org, Black Lives Matter and anti-Trump unions all have played a role – though there’s scant evidence to date that a singular group, let alone a Democratic campaign, is directing the protests that have become a near-daily occurrence.

College students, for instance, were at the center of the successful effort to shut down Trump’s rally Friday night at the University of Illinois at Chicago.

Students and student groups upset with the school allowing Trump to hold an event at the UIC Pavilion boasted online that they started hatching a plan nearly a week before the GOP front-runner’s arrival.

“Donald Trump has made ridiculous conspiracy accusations that this was a professionally staged protest with paid protesters,” according to the Facebook page “Stop Trump -- Chicago,” which the students say they started and maintain.

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“This was started by students, organized by students, and led by students,” says the post, put on the social media site Sunday night after a full weekend of Trump blaming Sanders, the Vermont senator and Democratic presidential candidate, for the rancor in Chicago and in several ensuing rallies in the Midwest.

The students weren’t entirely on their own, however. They acknowledge that the liberal, pro-Sanders group MoveOn.org donated 700 signs and a banner and sent an email to members informing them of the protest.

Trump has been adamant that Sanders’ “people” are driving the unrest.

At a rally Saturday in Cleveland, Trump said the protesters were “Bernie’s people. “

The next day, Trump told “Fox News Sunday” the Chicago agitators were hired pros.

“I mean, those were real professionals,” he said. “And they weren't protesters. They were … professional disrupters. They came in with the Bernie Sanders signs right out of his printing press.”

House Speaker Paul Ryan also said Tuesday “there is a concerted effort on the left” to disrupt rallies.

The Trump campaign, though, has not produced evidence that ‎"professional" organizers were behind those protests, and no other evidence has surfaced to back up the charge.  

The student organizers also deny it. “[A]dvertisement of a protest does not make them the organizers for it,” wrote Stop Trump – Chicago, which did not return a request for comment. “And as far as being ‘paid protesters,’ we would have loved to be paid for this but our students gladly did it for free.”

Sanders also rejected Trump’s allegations, releasing a statement calling Trump a “pathological liar” and saying, “Obviously, while I appreciate that we had supporters at Trump’s rally in Chicago, our campaign did not organize the protests.”

MoveOn.org, which has endorsed Sanders, did not return a request for comment. 

Trump spokeswoman Hope Hicks, though, on Monday stood by the argument that large forces are behind the protests, including ‘60s radical and former Weather Underground member William Ayers, once wanted by the FBI on bombing conspiracy charges until they were dropped in 1974 because of prosecutorial misconduct.

A picture of the 71-year-old Ayers, wearing a Black Lives Matters T-shirt while apparently standing outside the Chicago pavilion, can be found posted on several online sites.

And Ayers posted to his Twitter feed: “We shut Trump down! Beautiful gathering of anti-racist youth.”

Members of Black Lives Matters also have been engaged in Trump protests, wearing T-shirts that identify them as members of the group and chanting its motto, usually until they are escorted by security from the events.

In fact, Tommy DiMassimo, the student who on Saturday tried to rush Trump on stage at an Ohio campaign event, has ties to Black Lives Matters. The Wright State (Ohio) University senior also is seen in an online video, uploaded last year, dragging a U.S. flag while walking across campus with a group of mostly black protestors.

Trump said over the weekend that the individual “probably” was linked to ISIS. He appears to have made the ISIS connection after seeing the video, which is played over Arabic music with Arabic writing scrolling along the top.

DiMassimo told CNN he wanted to confront Trump because he is “a coward” and to show America that some people are not afraid of the billionaire businessman.

But he denied being a member of ISIS or having any connection to the terror group.

SEIU, the country’s biggest public-sector labor union, also was involved in the Chicago protest that forced Trump to cancel the rally.

Joe Iosbaker, the leader of SEIU Local 73, which represents roughly 3,000 UIC employees, acknowledged to Politico that he participated in the protests.

And he explained in a 1,085-word essay in the online publication “Fight Back! News” how the students planned the protests, including a strategy for “confronting the police.”

FoxNews.com’s Joseph Weber and Fox News’ Jason Donner contributed to this report.