The Prime Minister’s Office has been withholding from the RCMP an email about the $90,000 cheque Stephen Harper’s former chief of staff wrote to Sen. Mike Duffy, CTV News has learned.

RCMP investigators have been trying to obtain the email ever since CTV News first revealed its existence two months ago.

The prime minister’s communications director, Andrew MacDougall, confirmed that the email exists.

“My understanding is it is a paraphrase of conversations that happened,” he told CTV’s Ottawa Bureau Chief Robert Fife. “I’ve had them described to me from someone who is no longer here.”

The Feb. 20 email describes a secret deal to have Harper’s then-chief of staff Nigel Wright personally bail out Duffy, a Conservative senator who improperly claimed $90,172 in living expenses and faced the public release of an audit of his spending.

In the email, Duffy tells his lawyer that Wright worked out a “scenario” where all of his invalid expenses would be covered, including “cash for the repayment.”

Under the arrangement, Duffy would claim that he personally repaid his debt to taxpayers and the government would use its influence to blunt the outcome of the external audit.

A Conservative-dominated Senate committee subsequently whitewashed a damning audit report on Duffy’s expenses, which highlighted problems with his residency claims and per diems collected when he wasn’t in Ottawa on Senate business.

After CTV News broke the story, Wright resigned and Duffy left the Conservative caucus to sit as an Independent.

The Mounties subsequently launched an investigation into Wright’s payment to Duffy. The lead investigator has contacted CTV News twice to ask about the Feb. 20 email. In order to protect his sources, Fife told the Mounties to ask the PMO for the information they need to conduct their investigation.

But insiders say the Prime Minister’s Office has been withholding that information.

Asked if Wright himself has the email in question, MacDougall said: “I can’t speak for Nigel.”

RCMP affidavits allege that three other senior PMO staffers, including Harper’s former legal counsel Benjamin Perrin, knew of the deal between Wright and Duffy.

Perrin said he was never consulted on, or participated in, the deal. The Mounties say they have not yet been able to arrange an interview with Perrin.

Harper has maintained that Wright acted alone when he wrote a personal cheque to Duffy.

But NDP ethics critic Charlie Angus said PMO staff “clearly” knew about the email.

“So we are being told: ‘Well, we don’t really know what happened to it. Oh well, it’s not around anymore.”

Liberal MP Rodger Cuzner said the RCMP should obtain warrants to get the email about the Wright-Duffy deal from the PMO.

Fife reported Tuesday that the Mounties would prefer to see the PMO voluntarily provide all of the relevant information and require anyone with knowledge of the Wright-Duffy deal to come forward.