At least four other jet manufacturers are now in the running to replace Canada’s aging fleet of war aircraft, after it was revealed that the cost of buying and servicing F-35 fighter jets has ballooned to more than $40 billion.

The Conservative government was forced to look at alternatives after a yet-to-be publicly released report showed the cost of 65 jets over 36 years will far exceed the initial estimates of between $14.7 billion and $16 billion.

The early figures were based on a 20-year aircraft maintenance program.

The government is now changing its jet procurement process to include decision-making by senior officials and advice from independent experts.

CTV News has learned that those experts will include retired Lt.-General Charles Bouchard, who led the NATO mission in Libya, former auditor general Denis Desautels and University of Ottawa professor Philippe Lagasse, a critic of the F-35 plan.

The government is currently reviewing the F-35 report and plans to respond with a "comprehensive public update" next week before the House rises for Christmas break on Dec. 14.

“Our government has a seven-point plan for the replacement of the CF-18 aircraft,” House Leader Peter Van Loan said during question period Friday.

Meanwhile, interim Liberal Leader Bob Rae called for the resignation of Defence Minister Peter MacKay, saying his handling of the F-35 file has been unacceptable.

Rae said MacKay has to be held responsible for the "fiasco."

"I don't see how the minister of defence could possibly continue in his job. He's basically been a salesman for Lockheed Martin, the manufacturer of the F-35, since he took office," Rae told reporters.

Earlier reports from both auditor general Michael Ferguson and Parliamentary Budget Officer Kevin Page have said the government's estimates were far too low.

Ferguson accused the Defence Department of low-balling the estimate by not including operating expenses, and said it would actually cost more than $25 billion, but government officials denied trying to hide anything.

Page had estimated it would cost $29.3 billion to purchase and maintain the jets.

MacKay attributed the discrepancies to different accounting practices used to come up with the estimates, saying the higher numbers factored in costs such as fuel and maintenance for years down the road, while the government's estimates did not.

Though it was a previous Liberal government that first commenced Canada's participation in the F-35 procurement program more than a decade ago, the Liberals in recent years have maintained that Canada must hold an open and competitive bidding process to find a manufacturer for Canada's next generation of stealth fighters.

The government announced in 2010 that it was purchasing the F-35s as a replacement to the Canadian Forces' aging fleet of CF-18 fighter jets. The sole-sourced, untendered contract was part of a purchase deal entered into with other NATO members.

Rae said the government simply hasn't been up front and honest with Canadians.

"The government has misled Canadians consistently ever since the day they indicated this was the plane they were going to buy," Rae said.

With a report from CTV’s Chief Political Correspondent Craig Oliver