OTTAWA -- By early September, it had become clear to the Conservatives that their proposed F-35 fighter aircraft purchase had become a political millstone.

Polling numbers showed that more than 50 per cent of Canadians were against the project that was estimated to cost between $14 billion and $21 billion. It was debated in the Commons almost every day.

Defence Minister Peter MacKay acknowledged the controversial program might become a ballot box issue.

The Commons defence committee, upset about the secrecy, voted to start hearings into the F-35 deal. The first was set for Sept. 15. The Conservatives prepared a counterattack.

Industry Minister Tony Clement and Public Works Minister Rona Ambrose visited Canadian firms benefiting from the F-35 program.

No matter that many of those contracts had been in place for years.

After a number of efforts to sell the public on the F-35s, the Conservatives were now highlighting the work that would be headed to Canada's aerospace industry. As Clement explained on one tour: "Canada's participation in the Joint Strike Fighter program is yielding high-quality opportunities for companies and producing strong economic results across the country, with even more to come."

Industry Canada suggested the "even more to come" might be worth up to $12 billion. However, the Citizen has obtained government documents and talked to aerospace industry executives who challenge the figure.

A Joint Strike Fighter report done by the Pentagon in 2003 estimated Canadian firms would receive $3.9 billion in work. DND briefing notes from 2007 put the estimate at $5 billion. Both figures were based on Canada's purchase of 80 aircraft, as well as the U.S. and allied acquisitions.

In 2008, without explanation, the Tories raised the estimate to $8 billion. By the summer of 2010 - with the F-35 purchase under fire - Industry Canada was promising $12 billion worth of work. When the Citizen asked Industry Canada specialists to explain how they reached that number, the department did not respond.

While the value of predicted business climbed, the numbers of planes to be purchased by Canada dropped to 65.

Previously, DND had warned that reducing the F-35 purchase would cut into the work domestic firms would receive. "It will impact it quite substantially," Mike Slack, a senior official involved with DND's Joint Striker Program, advised in a 2007 interview.

Marc Garneau, the Liberal industry critic, warned that the figure can't be trusted. "There will be enormous pressure to keep jobs in the United States. There is no clear contractual arrangement here that says Canada must receive a certain proportion of work."

Aerospace industry representatives and DND officials acknowledge that unlike previous procurement programs, there are no guarantees Canadian companies will receive work from aircraft manufacturer Lockheed Martin.

It hasn't stopped unions from asking. The Canadian Auto Workers, which represents 10,000 aerospace employees, recently told a Commons committee that Canada should receive work equal to the value of the JSF purchase.

"Canadian workers should not be asked to just sit back and hope that Lockheed Martin will send contracts to Canada out of the goodness of its heart," said Jerry Dias, assistant to CAW president Ken Lewenza. "Wishful thinking is not how you build a world-class aerospace industry."

But Alan Williams, DND's former head of procurement, says Canada gave up guarantees when it selected a CF-18 fighter aircraft replacement without competition.

The Conservatives are also working to downplay concerns about the maintenance costs associated with the JSFs.

In 2009, a senior DND official told U.S. industry that price tag would be $12 billion. Another government document leaked to the media put the 20-year cost at $7 billion.

With growing opposition in the Commons, MacKay and DND came up with a new figure - $5 billion over the next two decades.

On Nov. 18 in the Commons, Conservative MP and former fighter pilot Laurie Hawn contradicted MacKay. "The $7 billion is a very well-educated estimate of what it will cost to support the aircraft for 20 years," he said.

Williams says there's no way to provide an accurate figure since the F-35 has not flown long enough.

Dan Ross, DND's assistant deputy minister for matériel, recently told MPs on the Commons defence committee that another unknown factor related to maintenance involves the F-35's computer software. With eight million lines of software code, some military officers liken the plane to a flying hard-drive. "We are not absolutely sure at the present time what level of third- and fourth-line maintenance will be done by individual partners, or will need to be done," Ross acknowledged. "We are about six years away from our first aircraft. We will be able to determine what that looks like at that time."

More problems with the F-35, including malfunctioning parts, have surfaced, although Lockheed Martin officials insist this is normal when an aircraft is being developed and tested. In addition, U.S. export laws could prevent Canada and other allies from receiving spare parts to keep the planes flying, a problem DND's Mike Slack says allies are trying to work out.

Slack insists the JSF program is proceeding smoothly. He assured Canadians that despite reports to the contrary, each plane will cost Canada between $70 million and $75 million.

Slack says he's talked to F-35 partner nations. Despite media reports, he says, all support the program.

By the fall, political positions on the Joint Strike Fighter had solidified: The Conservatives had made it their top defence priority; the Liberals vowed they'd run a competition for new aircraft - if elected; the NDP stood opposed; the Bloc Québécois was in favour it as long as Quebec firms received their share of work.

In November, the Defence Department launched a new public relations offensive on the F-35, this one to convince military analysts and academics on the need for the plane. Military officers say no other aircraft on the market will fit Canada's future requirements.

Even now, there is criticism of the purchase. Harry Swain, the former deputy minister for Industry Canada, has called the deal into question, pointing out that military equipment programs are always more expensive than predicted.

Auditor General Sheila Fraser has suggested the purchase will be risky.

Williams questions the rush to purchase, pointing out that the CF-18s can continue to fly until 2020. He notes that the JSF is still being tested and has yet to be proven.

"The JSF could turn out to be an excellent aircraft, but we don't know that at this point," he says. "Why the rush? Why not run a competition and see if it can win on its merits."