Donald Trump’s widely criticised response to violence by neo-Nazis and white supremacists in Charlottesville, Virginia last month was an instance of the president “taking it up to a higher level”, former White House counselor Steve Bannon has said.

Steve Bannon is back at Breitbart. But can his page of rage survive an ad boycott? Read more

In excerpts of an interview with CBS 60 Minutes host Charlie Rose set for broadcast on Sunday, Bannon also said Trump’s chief economic adviser Gary Cohn “should resign” and said the Catholic church was “terrible” on immigration issues such as the future of Dreamers because “they need illegal aliens to fill the churches”.

One counter-protester was killed and many injured in Charlottesville after a man drove a car into a crowd. Trump said blame for the unrest rested “on many sides” and was slow to condemn the white supremacists who organized the event, a protest against the planned removal of a statue of Confederate general Robert E Lee.

Trump belatedly condemned the militant white supremacists, yet insisted there were “some good people” attending their rally. He also lamented the removal of statues to Confederate leaders.

Trump’s remarks provoked widespread uproar, not least among Republicans. Bannon said he was the only one of Trump’s staff to defend the president unequivocally, and said he had told White House chief of staff John Kelly how important that was.

“I was the only guy that said, ‘He’s talking about something, taking it up to a higher level’,” Bannon said. “What he was trying to say is that people that support the monument staying there peacefully and people that oppose that, that’s the normal course of – of first amendment …

“All Donald Trump was saying is: ‘Where does it end? Does it end in taking down the Washington monument? Does it end in taking down Mount Rushmore? Does it end at taking Churchill’s bust out of the Oval Office?’

“My problem – my problem, and I told General Kelly this – when you side with a man, you side with him. I was proud to come out and try to defend President Trump in the media that day.”

Bannon left the White House late in August and has returned to the far-right website Breitbart News, which he ran before joining Trump’s team. He said he would now be the president’s “wingman outside for the entire time, to protect.”

“You will not be attacking Donald Trump?” Rose asked.

“No, our purpose is to support Donald Trump,” Bannon said, “to make sure his enemies know that there’s no free shot on goal.”

House Speaker Paul Ryan, a frequent critic of Trump if not an outright enemy, told the New York Times on Thursday he believes Trump was “disgusted” by the neo-Nazis and white supremacists who marched in Charlottesville.

“I know he’s disgusted by these people,” Ryan said. “His kids, his grandkids are Jewish.”

Ryan said he believed Trump “made the right statements” on Charlottesville when he condemned white supremacy by name but not when he retreated from that position and appeared to draw a moral equivalence between those neo-Nazis who marched and those who protested against them.

“The point is every single one of us needs to be really clear about this,” he said.

CBS said Rose’s interview took place in the Capitol Hill townhouse Bannon uses as his headquarters, which his team calls ‘the embassy”, and said its host sat in on a Breitbart editorial meeting and interviewed key staff.

Rose asked Bannon if the media’s image of him from his time in the White House was correct. Bannon said it was. “I’m a street fighter.”

“By the way,” he continued, “I think that’s why Donald Trump and I get along so well. Trump’s a fighter. Great counter-puncher.”

Bannon also condemned leaks from the White House. He said: “If you are going to break with [Trump], you should resign. I’m talking, obviously, about Gary Cohn and some other people. That if you don’t like what he’s doing and you don’t agree with it, you have an obligation to resign.”

Cohn was the most senior administration official to condemn the president’s response to Charlottesville and was reported to have considered resigning.

Meanwhile, noting that New York’s Catholic cardinal Timothy Dolan opposed Trump’s decision this week to end the Daca program to protect young people brought to the country illegally as children from being deported, Bannon said the church was “terrible” on immigration issues.

“You know why? Because [they have been] unable to come to grips with the problems in the church, they need illegal aliens. They need illegal aliens to fill the churches. It’s obvious on the face of it,” Bannon said.

Dolan said in an interview on Thursday that it was “a preposterous and rather insulting statement.” He added that the Bible is “so clear that to treat the immigrant with dignity and respect, to make sure that society is just in its treatment of the immigrant is Biblical mandate.”