Prime Minister Stephen Harper's chief of staff is expected to step down from his post within weeks, CTV News has learned.

Sources told CTV News Wednesday night that Ian Brodie is set to leave his position -- most likely in July.

Earlier this year, the Tories were hounded by the opposition over reports of Brodie's alleged involvement in the so-called NAFTA-gate affair.

The affair dates back to the March leak of a Canadian consular document involving U.S. presidential hopeful Barack Obama.

The memo claimed that a senior adviser to Obama told Canadian diplomats that the presidential candidate isn't serious about renegotiating the NAFTA trade deal -- and suggested comments Obama would make on NAFTA are more about political posturing than a real policy plan.

In response, Harper launched a probe into the leak involving the Foreign Affairs Department. He also conducted an internal investigation. According to The Globe and Mail, a report has been completed, although it hasn't yet been released.

Pressure on Harper

Brodie is expected to leave his post just ahead of the release of the report in July.

But, in a press release Thursday, Liberal International Trade Critic Navdeep Bains called on Harper to release the Privy Council report on the NAFTA-gate leaks immediately.

"The government committed to releasing the report in the House of Commons, yet we now hear that the report is finished and sitting on Prime Minister's desk," said Bains.

"This report deals with leaks from the highest levels of the Conservative government and it is grossly inappropriate for the Prime Minister to delay its release."

Bains said if the report indicates that Brodie was the source of the leak then Harper needs to fire him immediately.

"This kind of blatant interference in the democratic process of another country, particularly a country like the United States, with whom we share such a vital relationship, cannot be swept under the rug," he said. "It is time Prime Minister Stephen Harper stops talking about accountability and starts showing some."

The Prime Minister's Office has not commented on reports of Brodie's departure.

Guy Giorno, who was chief of staff to former Ontario premier Mike Harris, is the rumoured replacement for Brodie.

Giorno knows Ontario well and he could help attract votes for Harper in an upcoming election, CTV's Graham Richardson said Thursday from Ottawa.

Giorno is currently with Fasken Martineau, a corporate law firm.

With files from The Canadian Press