“At this stage we are optimistic that Australia will be a customer for a very significant number, although what that number will be is still a little bit up in the air,” said Johnston.
Defense analysts predict Australia might end up buying between 50 and 70 of the fighters instead of 100, although Canberra could also buy the full number but over a longer timeframe beyond 2020, depending on a budget recovery.
Australian is also closely watching the budget battle in Washington, where $85 billion worth of spending cuts are due to kick in on Friday, hitting defense and possibly orders for 2,363 F-35s among the U.S. Air Force, Marines and Navy.
Lockheed is developing three variants for the United States and eight partner countries that helped fund the plane’s development - Britain, Australia, Italy, Turkey, the Netherlands, Denmark, Norway and Canada. Two other countries, Italy and Japan, have also placed orders.
Canada in December flagged it could cut plans to buy 65 aircraft, while Italy has also scaled back orders and Turkey has delayed its purchases by two years.
Australia is the second biggest international buyer after Britain, and its small air force is one of the most technically advanced in Asia and a pointer to emerging regional defense capabilities.
But a slowing of the country’s resources export boom is forcing the Labor government to look for savings.
Defense Minister Stephen Smith last May deferred an order for 12 F-35s by two years, and has so far contractually committed to buying only two.
The influential Greens party, which has the upper house Senate balance of power, failed to find support in parliament on Thursday to cancel Australian F-35 orders and put the estimated $13 billion saving into development aid.