Dominic Cummings continued the “people versus Parliament” rhetoric by saying the fury of some voters is unsurprising.
His comments come as the Church of England criticised MPs’ language as “not worthy of our country”.
Boris Johnson’s senior adviser criticised many MPs as being “disconnected” from what people think in the “real world”, as the Prime Minister refused to apologise over his controversial words.
Parliamentary tensions prompted around 120 archbishops and bishops on Friday to issue a statement warning against “further entrenching our divisions”.
The PM stoked tensions during fiery exchanges in the Commons where he repeatedly described attempts to block no-deal as the “surrender act”.
He also dismissed a Labour MP’s complaint that his “inflammatory” language risked provoking attacks as “humbug”.
He was facing calls to apologise for language that pits politicians against voters and was even criticised by his sister Rachel Johnson for using “strongman” tactics.
But the PM’s de facto chief of staff Mr Cummings risked further stoking tensions, as he answered questions after the book launch of a Vote Leave backer on Thursday night.
Asked if he blamed MPs for the abuse, Mr Cummings criticised them for not respecting the result of the 2016 referendum, adding: “It is not surprising some people are angry about it.”
Serious threats of violence
He said that both Leave and Remain campaigners have had “serious threats” of violence, which should be taken seriously.
“In the end the situation can only be resolved by Parliament honouring its promise to respect the result,” he added.
Mr Cummings described the current chaos as “a walk in the park” compared to the referendum during which he was Vote Leave campaign director.
“We are enjoying this, we are going to leave and we are going to win,” he added.
The College of Bishops stressed that “we should speak to others with respect”, adding that the result of the EU referendum “should be honoured”.
They also issued a warning amid fears following Mr Johnson’s defeat in the Supreme Court, where judges ruled his prorogation was unlawful.
“We call on politicians to adhere rigorously to the rule of law and on all to respect and uphold the impartiality of the courts and our judiciary,” the statement said.
“It is easy to descend into division and abuse – climbing out and finding unity again takes far longer.
“Further entrenching our divisions, whether from uncertainty or from partisanship, is not worthy of our country nor the leadership we now need.”
Wilfully destroying the prospects of cross-party agreement
Sir John Major was among those critical of the PM, accusing him of “wilfully” destroying the prospects of cross-party agreement on Brexit with his Commons onslaught on the opposition.
In a speech on Thursday, the Tory former prime minister said Mr Johnson was whipping up “fear and anger” for electoral purposes – a tactic he described as “profoundly un-Conservative”.
Chief among the criticism of Mr Johnson was over his comment that the best way to honour the murdered Remain-supporting MP Jo Cox was to “get Brexit done”.
On Thursday, Liberal Democrat leader Jo Swinson had to leave cross-party talks early so she could speak to police about a threat made to one of her children.
And Labour MP Jess Phillips disclosed that a man had been arrested while trying to smash the windows and kick the door of her Birmingham Yardley constituency office while yelling “fascist”.
Mr Johnson did not apologise for his words and instead called for a cooling of tempers.
“I think it is fair enough to call the ‘surrender act’ what it is. I think it is absolutely reasonable. But we do need to bring people together, and get this thing done,” he said.
“Tempers need to come down, and people need to come together because it’s only by getting Brexit done that you’ll lance the boil of the current anxiety and we will be able to get on with the domestic agenda.”
But Jeremy Corbyn said the PM’s use of terms like “betrayal” and “surrender” risked driving some people to “unbelievable extremes”.
“The Prime Minister’s language is encouraging people to behave in a disgraceful and abusive way to other public figures,” the Labour leader added.
The PM’s pro-Remain sister hit out at his “strongman” tactics, accusing him of using the Commons despatch box as a “bully pulpit”.
“What we are seeing is an executive that is so keen to deliver Brexit in any shape or form… they will do anything to justify that end,” Ms Johnson added.
Meanwhile, opposition leaders were calculating ways to prevent the PM from refusing to ask for an extension to Brexit if MPs do not agree a deal as demanded by the Benn Act.