Donald Trump Jr. and Kimberly Guilfoyle left the stage during a joint speech Sunday in Los Angeles after a cabal led by a far-right Holocaust denier feuding with the event's sponsors shouted them down and demanded a question-and-answer session.

The pair were promoting Trump Jr.'s book, 'Triggered: How the Left Thrives on Hate and Wants to Silence Us.' But it was a fringe faction of conservatives who complained loudly after Turning Point USA announced that the planned Q&A session had been canceled.

Video from the event shows chants of 'USA' being drowned out by shouts of 'Q and A' and 'America First' among an audience that The Guardian estimated at 450 people. A source close to Trump Jr. put the total at 1,000.

Guilfoyle, Trump Jr.'s longtime paramour who has tag-teamed dozens of public appearances with him, tried to scorch the small group of far-righters, saying she wouldn't engage with them 'because you're not making your parents proud by being rude and disruptive and discourteous.'

'Let me tell you something,' she shouted as the chanting grew louder. 'I bet you engage and go on online dating. Because you're impressing no one here to get a date in person.'

A far-right cabal led by a Holocaust denier shouted Donald Trump Jr. and Kimberly Guilfoyle off the stage at UCLA on Sunday after event organizers with a pro-Trump youth group called Turning Point USA announced that a planned Q&A portion of the book tour speech had been called off

A large crowd turned out to see Trump Jr. and Guilfoyle; a source close to the president's eldest son said they spoke for more than the allotted hour and only left the stage when white nationalist protesters demanded a platform with a Q&A session

Protesters from fringes on both the left and right shouted at Trump Jr. and Guilfoyle

The source close to Trump Jr. said Monday that he and Guilfoyle spoke longer than the hour they had promised to stay on stage, and disputed the contention that the far-right protesters drove them out.

The chaos underscored a vicious civil war inside the Republican Party's most active and vocal youth culture – between the Trump-friendly Turning Point USA and a breakoff 'America First' movement led by firebrand white nationalist YouTube host Nicholas Fuentes.

Fuentes, 21, calls himself an 'American nationalist.' He and his followers profess to be supporters of President Donald Trump, but America's Republican mainstream has shunned them for gleefully doubting that the Nazis killed 6 million Jews in a World War II Holocaust.

Comparing ovens in Nazi death camps to ovens a baker would use to make cookies, Fuentes said during an October 30 YouTube broadcast that it would take too long to 'bake' that number of Jews.

'How long does it take Cookie Monster to make 6 million batches of cookies?' he joked. 'I don't know – it certainly would be five years, right? The math doesn't seem to add up there.'

Claiming that overhead photos of Nazi death camps don't show a sufficient number of smokestacks, Fuentes claimed that 'if you look at the soil texture, it's really not deep enough for mass cookie-storage underground.'

Kimberly Guilfoyle, Trump Jr.'s longtime girlfriend, mocked the white nationalist fringe group in the UCLE crowd on Sunday, saying they probably had to resort to online dating

'Six million cookies? Uh-uh. I don't buy it,' he said, later claiming that the analogy was 'all irony. I love and respect everyone.'

Neither Trump Jr. nor his spokesman, nor Guilfoyle, responded to requests for comment early on Monday.

But the president's son said Sunday on stage that 'the reason oftentimes it doesn't make sense to do the Q&A is not because we're not willing to talk about the questions. Because we do. No, it's because people hijack it with nonsense looking to go for some sort of sound bite.'

'You have people spreading nonsense, spreading hate, trying to take over the room,' he said.

The source close to the president's eldest son said he was against 'giving a platform to a bunch of neo-Nazis' and 'doesn't want people like that to be Trump supporters.'

A strong police presence accompanied the pair, according to CBS-TV2 in Los Angeles.

Fuentes has bitterly sniped at Turning Point for more than a year, reacting to efforts by the group and its founder Charlie Kirk to distance themselves from white nationalists – including some who participated in a 2017 'Unite the Right' event that left a woman dead in Charlottesville, Virginia.

According to The Boston Globe, Fuentes was among them.

Here's Nick Fuentes denying that the Holocaust happened.



Him and his followers are scum of the earth and their bad faith, anti-Semitic attacks should be shot down by the entire conservative movement. pic.twitter.com/7wJ9S7Q6zv — Caleb Hull (@CalebJHull) October 30, 2019

Nick Fuentes, a self-described Donald Trump supporter who is considered part of America's fringe white nationalist movement, compared Jews incinerated during the Nazi Holocaust to 'cookies' last month, doubting publicly that 6 million of them were slaughtered during a World War II genocide

The Boston Globe has reported that Fuentes participated in the 2017 'Unite the Right' white nationalist rally in Charlottesville, Virginia that turned violent and left a counterprotester dead

He appeared to take a victory lap after Trump Jr. and Guilfoyle walked out, sharing dozens of gleeful tweets mocking Turning Point.

'Our problem is not with [Trump Jr.] who is a patriot – We are supporters of his father!' he tweeted. 'Our problem is with Charlie Kirk's TPUSA organization that SHUTS DOWN and SMEARS socially conservative Christians and supporters of President Trump's agenda. We are AMERICA FIRST!'

Fuentes, whose splinter following has dogged Kirk and Turning Point on college campuses all year, vented last week on YouTube that as the group hosts Trump Jr.'s book tour events, it is 'literally campaigning for Trump, and they have to discriminate against his voters.'

'People do not go to a "free speech" thing and get dragged to the back of the line, kicked out, because they don't fit the profile of what a questioner is supposed to look like,' he said.

One central theme in Trump Jr.'s book is the claim that liberal partisans are increasingly unwilling to debate ideas but instead often prefer to silence their critics.