U.S. Republican front-runner Donald Trump took heat for initially not denouncing the endorsement of former Ku Klux Klan leader David Duke.

"I know nothing about David Duke, I know nothing about white supremacists, and so you're asking me a question about people I know nothing about," Trump recently told CNN's State of the Union.

Trump later stepped back, blaming a bad ear piece, saying he couldn't hear the questions clearly.

But how much weight does that kind of a statement have in the United States?

The Southern Law Poverty Centre tracks the KKK. It says the number of chapters of the hate group jumped from 72 in 2014 to 190 last year.

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Trump has targeted Muslims, saying 'These are people that only believe in jihad.' (Reuters)

The number of militia groups was also on the rise. All this, when not long ago, the U.S. elected its first-ever black president.

"A lot of resentment in certain quarters of the white population here, against not only a black man in the White House, but what that black man represents. And what I'm talking about is the coming loss of a white majority in the United States over the next 30 years," said Mark Potok from the Southern Poverty Law Center.

Add to that the country's economic slowdown, which has affected all races in terms of jobs, wages and security.

Number of hate-based attacks on the rise

"I think racism explodes when there is anger, when there is hardship, people want to target, and they feel free to attack that target," said Julian Sher, who works for CBC's the fifth estate.

Julian Sher

Julian Sher is the Senior Producer of CBC television's the fifth estate. He wrote the 1983 book White Hoods: Canada's Ku Klux Klan. (Julian Sher)

He literally wrote the book on Canada's history with hate groups, with his 1983 book White Hoods: Canada's Ku Klux Klan.

Sher said Trump is the loudest and latest politician to appeal to the KKK.

"If you have a political leader who's attacking minorities, Muslims, people who are vulnerable, then people who are feeling pressured, who are out of work, feel the elites have stolen money, stolen their country, are going to have a reason to be angry, but also have a target that they feel now is safe," he said.

Trump has targeted Muslims, saying "These are people that only believe in jihad."

He's said that illegal immigrants are rapists who bring drugs and crime to the U.S. Trump has also said he will build a wall along the U.S.-Mexico border. 

And several days ago, a black protester was shoved around at one of his rallies.

In Canada, organizations that track anti-Muslim and anti-Semitic attacks say they've never seen as many hate-based attacks as they have in the past year, including the burning down of a mosque in Peterborough after the November Paris attacks.

"I think the biggest difference between Canada and the U.S., and we're seeing this with Trump and the U.S. elections now, is the hate groups in Canada don't have the same political echo chamber that they have in the States," said Sher.

And the danger is that these hate groups see hope in Trump, who they see as having given them a voice.

"It`s really quite irrelevant whether Trump himself personally approves or disapproves of the Klan. The point is, that in very lightly-coated language, Trump is essentially appealing to the very same constituency that the Klan is appealing to," said Potok.

Hitler comparisons

Trump's decision not to denounce the KKK's support has drawn comparisons to Adolf Hitler, and how he came to prominence in Germany in the 1930s.

Saturday Night Live made parody commercials for Trump, likening his followers to Nazi supporters.

SNL tackles U.S. presidential race with Donald Trump spoof3:43

Comedian Louis C.K. also chimed in — he sent an email to many of his fans and followers asking Republicans to stop voting for Trump, saying it was funny for a while but now it's serious.

"He's an insane bigot. He is dangerous," he wrote. "The guy is Hitler. And by that I mean that we are being Germany in the 30s ... Hitler was just some hilarious and refreshing dude with a weird comb over who would say anything at all," he wrote.

With files from CBC's David Common