Canada's beleagured Defence Minister accused his political opponents of dishonesty even as Harjit Sajjan faced another day of grilling in the House of Commons over his now-retracted claim to have been the architect of a major battle in Afghanistan.

Mr. Sajjan and fellow Liberal MPs kept trying to shift the conversation to the inconsistent record of investment in defence spending as the Conservatives and New Democrats used time allocated for opposition priorities to table and debate a non-binding motion of non-confidence in Mr. Sajjan.

The Defence Minister apologized recently for taking credit as the architect of Canada's largest battle in Afghanistan but he also has faced allegations from the New Democrats that he's playing down his connections to the detainee controversy during the combat mission where Canadians handed over prisoners to torture by Afghan authorities.

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Mr. Sajjan faced off against his accusers in the Commons Monday where opposition MPs tried to make the case that he should no longer serve as Defence Minister. The motion says "the House has lost confidence in the Minister of National Defence's ability to carry out his responsibilities on behalf of the Government since, on multiple occasions the Minister misrepresented his military service and provided misleading information to the House."

A vote on the matter is expected Tuesday and the Liberal majority in the Commons is expected to flex its muscle so the motion cannot pass.

Mr. Sajjan, however, used the opportunity to hammer his main political rivals, the Conservatives, over a vulnerability in their record on the military. He cited how military spending dropped during the years the Harper government was in power.

"I know the Official Opposition does not like to deal in facts when it comes to defence, but there is a fact it cannot ignore: Canada's defence spending, as a proportion of GDP, was considerably lower when the Conservatives were removed from office than when they came in," the Defence Minister told the Commons.

He explained how deficit-fighting cuts in the Harper era reduced the money flowing to the Forces. "By the time these were were fully implemented in 2015, each reduced the annual defence budget by $1-billion, for a total of $2-billion per year."

Conservative defence critic James Bezan said Mr. Sajjan's mid-April description of himself as the "architect of Operation Medusa" was not the first time he had made this claim.

"Video evidence shows that he first said this in 2015 when he was campaigning as the Liberal candidate to become the member of Parliament for Vancouver South. He said it quite openly. We do not know how many times that has been repeated behind closed doors or in meetings," Mr. Bezan said.

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"He has continually misled the House and Canadians and that his behaviour is demoralizing our troops, has caused our veterans to be incredibly angry and we also know that our allies are going to have trouble taking him seriously. There is a credibility issue here."

Mr. Sajjan refused to be drawn into a debate about his past statements. "I am focused on making sure our men and women have all the necessary tools so they can fulfill their missions at home and abroad."

Separately, the Trudeau government was urged to kill plans to buy Super Hornet fighters as a stopgap measure for the Royal Canadian Air Force.

The Senate national security and defence committee said it makes little sense to buy a second type of plane as a short-term replacement even as Canada is searching for a third model to serve as its long-term replacement fighter.

The Liberals are planning to order 18 Super Hornets to help shore up the military's fighter capabilities while they hold a competition for a bigger number of warplanes to replace Canada's aged CF-18 Hornets. The Liberals say this is necessary because the air force suffers from a "capability gap" right now where it has too few CF-18s on hand.

Boeing's Super Hornets first entered service in 1999.

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The Senate committee said in a new report, Reinvesting in the Canadian Armed Forces: A Plan for the Future, that the interim Super Hornet purchase would hinder more than help. The committe cited expert testimony saying that the long-term costs of a stop-gap deal – $5-billion to $7-billion – would outweigh any short-term savings and that the Super Hornets would also hinder Canada's ability to fly alongside its allies.

Instead, senators are urging the federal government to hold a quick competition to pick a permanent solution for Canada's next fighter plane and make a decision by end of June, 2018.