Defence Minister Harjit Sajjan, under pressure to deliver a new purchasing plan for big-ticket military goods, is preparing to lower expectations for the amount of cash available by blaming the former Conservative government for leaving the Canadian Armed Forces with a multibillion-dollar budget shortfall.

Mr. Sajjan will deliver a speech in Ottawa on Wednesday that will lay out the lack of available funds for essential procurement projects into the next decade, arguing that this is creating unexpected challenges for the long-term plan for the CAF, federal officials said.

After a series of delays, the results of the defence policy review are expected to be unveiled in coming weeks, the officials said.

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Campbell Clark: Harjit Sajjan makes no excuses – there aren't any

Mr. Sajjan, who had to apologize on the weekend for overstating his role as an officer in the war in Afghanistan, is now facing pressure to deliver on the Liberal Party's 2015 promise for a "leaner, more agile, better-equipped military."

However, defence officials said the minister will clearly lay out to Canadians that he is facing budget constraints that go well beyond the expectations of most military experts.

"We need to get more hard facts into the public domain about the real state of affairs and where we're starting from. It has made the challenge deeper than it was widely understood to be going in," said a senior defence official, speaking ahead of the speech on condition of anonymity.

In particular, defence officials said there are 18 major projects, which are all essential to the continuing operations of the Armed Forces, that are currently unfunded. As such, any future budget increases awarded to the Department of National Defence would have to go to these projects rather than to new purchases that will be called for in the defence policy review.

The unfunded projects include a replacement fleet for Canada's decades-old Aurora aircraft, new communications satellites for the Arctic, new military-grade bulldozers and new refuelling trucks. All together, these projects are worth well more than $10-billion, with additional needs to train CAF members.

But the Conservative Party, which is calling for Mr. Sajjan's resignation for having called himself the "architect" of Operation Medusa in Afghanistan in 2006, is refusing to shoulder the blame for DND's current budget problems.

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"I'm very concerned that our Armed Forces will be hollowed out, as they have been by previous Liberal governments," Conservative MP James Bezan said. "In terms of hard dollars, we were spending more than they are by quite a bit."

Meanwhile, Canada's Ethics Commissioner Mary Dawson is facing new pressure to reopen an investigation into whether Mr. Sajjan violated the Conflict of Interest Act by refusing to open an inquiry in the Afghan detainee controversy.

During Canada's combat mission in Afghanistan's Kandahar province, prisoners captured by Canadian soldiers were handed over to Afghanistan's notorious National Directorate of Security, where they were tortured to produce intelligence that could help the fight against the Taliban.

Mr. Sajjan, a former reserve soldier who served in Afghanistan, declined to open an investigation into Canada's role in the matter, saying Canadian troops' handling of the detainees was in accordance with international law.

When Ms. Dawson questioned him about his involvement in the detainee matter, Mr. Sajjan told her "at no time was he involved in the transfer of Afghan detainees, nor did he have any knowledge relating to the matter."

However, NDP Leader Tom Mulcair is now pointing to praise for Mr. Sajjan's intelligence-gathering role in Kandahar, such as a letter from a superior saying the minister was a key liaison with Afghan forces, including the Afghan National Police.

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"This information casts further doubt on the minister's truthfulness in the account of his role that he provided to you. It is simply not plausible for a military intelligence liaison officer who had such a role on the battlefield to have had no access whatsoever to information relating to the capture and transfer of Afghan detainees," Mr. Mulcair wrote in a May 2 letter to Ms. Dawson.

"This is a clear conflict between the minister's responsibilities and his personal interests regarding events before his appointment."

The issue of procurement has long been a challenge for governments of all stripes.

Back in 2008, the Conservative government laid out a Canada First Defence Strategy that would build 15 ships to replace existing destroyers and frigates, buy 65 new fighter jets and 17 fixed-wing search-and-rescue planes, among other items.

Mr. Sajjan is expected to make the case on Wednesday that Canada will need much more than 65 fighter jets when it buys its next fleet in coming years, adding billions to the final price tag.

Vice-Admiral Mark Norman publicly warned Canadians of this funding shortfall shortly after the Liberals won election under Justin Trudeau. The veteran officer, now suspended pending the outcome of an RCMP probe into the leak of confidential information, went public in late 2015 with a frank discussion of the lack of sufficient money allocated to building Canada's future fleet of military ships.

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He said in December, 2015, when he was head of the Royal Canadian Navy, that the military would need twice as much money set aside for warships, saying the initial cost estimates of $14-billion had doubled and would cost as much as $30-billion.

The Liberal Party has historically found itself divided over military spending, which tends to restrain its enthusiasm for funnelling cash into the Department of National Defence.

But the Conservative Party, which is avidly pro-military, nevertheless delivered far less than it promised for the Forces during nearly a decade in office. The government of Stephen Harper had a few early successes in its mandate – such as heavy-lift aircraft – but then quickly became bogged down in efforts to deliver planes and ships.

Military procurement has proven difficult for successive governments over the decades. For example, it was only in 2015 that Ottawa finally took delivery of the first six of 28 naval helicopters originally ordered more than a decade ago. Former Harper defence minister Peter MacKay called that helicopter purchase the "worst procurement in the history of Canada."