Conservative Leader Stephen Harper, campaigning in Hay River, N.W.T., today, would not acknowledge that his current chief of staff Ray Novak knew about Nigel Wright's $90,000 payment to Senator Mike Duffy, despite emails filed as evidence in court pointing to the contrary.

"I will send my cheque on Monday," Wright, Harper's former chief of staff, wrote to Novak and Benjamin Perrin, lawyer for the Prime Minister's Office, in an email on March 23, 2013.

In 2013, Novak was Harper's deputy chief of staff. The email was filed as evidence on Thursday during Wright's second day of testimony in Duffy's criminal trial in Ottawa.

Harper was asked why Novak was not reprimanded for his actions, but rather promoted since that day, when Wright told him of his payment to Duffy.

"I would simply not accept the premise of that question, Harper said. "These are the actions of Mr. Duffy and Mr. Wright.

"You hold people responsible for their own actions; you certainly don't hold subordinates responsible for the actions of their superiors," Harper said on Friday.

'Vast majority' led to believe Duffy repaid

Friday marked the third day in a row that the Conservative leader was faced with questions arising from Wright's testimony and evidence filed in the criminal case of Duffy, a senator he appointed in 2008.

Stephen Harper's current chief of staff Ray Novak (right) was copied on a 2013 email from Nigel Wright about his $90,000 payment to Senator Mike Duffy. The email was filed as evidence in Duffy's criminal trial this week. (Sean Kilpatrick/Canadian Press)

Duffy has pleaded not guilty to 31 charges of fraud, breach of trust and bribery related to expenses he claimed in 2013 as a senator and later repaid with money from Wright.

"These are the two people who are responsible and they are being held accountable," Harper said to loud applause from the crowd invited for the Conservative election campaign event in Hay River.

Harper maintained that it was not only his understanding, but the understanding of his senior staff that Duffy would be made to repay his ineligible expenses — not that Wright would pay them for him.

"We are all told that Mr. Duffy had repaid his expenses. Mr. Duffy said that on national television, he had borrowed money from the bank, etc. That is what we all understood to be the truth."

"That is what the vast majority of — that's not what only the entire caucus thought and I thought, that is what the majority of our staff also believed was the case," Harper said.

'Rogue elements' responsible?

Harper repeated that when he found out that was not the case, he made it "very clear to the Canadian public."

In fact, Harper made it public once it had been reported in the news.

Harper initially said that Wright had "offered his resignation" and that he'd accepted it. But in a radio interview months later, Harper flip-flopped and said Wright had been "dismissed."

NDP Leader Tom Mulcair said, further to the evidence filed in court this week, he simply does not believe that Harper was kept in the dark about a plan that saw senior staff in the Prime Minister's Office working closely with Conservative senators to have Wright repay Duffy's expenses, in exchange for the senator saying he'd repaid them himself.

"Mr. Harper would have us believe that these were rogue elements within his office who did this without letting him know anything about what was going on, but the thing is — if they were out of control and not reliable people … how come he's kept them all in his office?

"That's just not credible," Mulcair said from a campaign stop in the Toronto riding of Eglinton-Lawrence on Friday.

Harper urged to fire Novak

Mulcair also said "the excuse" by the Conservative campaign that Novak, Harper's current chief of staff, did not know of Wright's payment to Duffy was implausible.

A Conservative campaign spokesman said on Thursday that Novak never saw the email in question.

Liberal Leader Justin Trudeau did not have any campaign events on Friday, but Dominic LeBlanc, the Liberal incumbent for the New Brunswick riding of Beauséjour, spoke to reporters outside the Ottawa courthouse.

LeBlanc called on Harper to fire Novak and remove those senior members of his inner circle who were "intimately involved" in a plan to make Duffy's expense problems go away.

"When Mr. Novak ultimately gets fired, it won't be because of some principled position, it'll be because the heat got a little heavy and Mr. Harper couldn't hide from the heat in the Far North."

LeBlanc said Harper should also remove the party's chief fundraiser, Senator Irving Gerstein, and Marjory LeBreton, a senior adviser on his campaign, for their role in the scheme.

Harper was in Hay River to announce that a re-elected Conservative government would make further improvements to a stretch of Highway 5 running through Wood Buffalo National Park in the Northwest Territories.