Right-wing backers of President Donald Trump posted the number of the Iowa caucuses reporting hotline on 4chan and encouraged flooding the lines, exacerbating problems already disrupting the caucuses, NBC and Bloomberg reported.

“Clog the lines,” several participants urged on the often-extremist internet message board after the caucuses’ voting reporting app malfunctioned and forced precinct chairs to report results via the hotline.

Soon, the phone volunteers who were supposed to be recording caucus results from precinct chairs on Monday night were also fielding calls from trolls attacking Democrats and expressing support for Trump. Other callers simply tied up the lines, then hung up when volunteers answered.

Democratic Party leaders were told of the phone attack in a conference call Wednesday night, Bloomberg reported.

The communications director for the Iowa Democratic Party, Mandy McClure, confirmed in a statement that there was an “unusually high volume of inbound phone calls to its caucus hotline, including [by] supporters of President Trump.” The “unexplained and at times hostile” calls “contributed to the delay in the Iowa Democratic Party’s collection of results,” she added.

Some 4chan users boasted online about their impact by posting increasing wait times on the message board, while others continued to urge more phone calls. “Make the call lads,” said one. “Uh oh, how unfortunate it would be for a bunch of mischief makers to start clogging the lines,” another reportedly mocked.

Rob Sand, Iowa’s state auditor, said the huge influx of calls appeared to have been triggered by an internet post. “A lot of calls came in at a certain point where it was clear somebody had published the hotline number somewhere,” Sand told NBC.

Other volunteers and Democratic Party staff members noted repeated fake calls and blocked the numbers from callers who were apparently trying to deliberately disrupt the process.

According to NBC, some on 4chan later denied being responsible for caucus night problems. Trump campaign communications director Tim Murtaugh said officials “don’t know anything about this,” adding: “It’s laughable that they would try to blame Trump for their own incompetence.”

Participants on 4chan, who are anonymous, have a reputation for political trolling and online harassment campaigns. They often swarm online polls or flood comments to skew results. It wasn’t immediately clear if a deliberate disruption of the Iowa election reporting process could be prosecuted as a crime.