PRESSURE over his future has forced Prime Minister Tony Abbott to promise South Australia a crack at the lucrative Future Submarines project.

Mr Abbott needs all the votes he can get to defeat a spill motion in the partyroom on Monday and SA Senator Sean Edwards had made his support for Mr Abbott as PM contingent on SA being able to tender for the subs.

On Sunday night, Mr Abbott said that “you would expect the Australian Government to want to get the best product and you would expect the Australian Government to give Australian suppliers a fair go.’’

As he tries to shore up numbers he has promised Senator Edwards that shipbuilder ASC will be able to tender for the job, which is worth between $20 and $40 billion.

Senator Edwards said it was “fantastic news” that there was now a commitment to a full and open tender process which will let ASC show whether it can do it.

“I now call on the management of the ASC and the unions to come together like they never have before and prove that the faith I’ve had in them through the period from the 14th of October when I commenced my lobbying of the PM that they can be the world class, competitive builder of submarines that they say they can be,” he said.

There are fears within the industry that the job would be handed to Japan, whose Soryu-class submarines could form the base of a new design for Australia.

Mr Abbott and his former Defence Minister David Johnston have been under fire for walking away from a promise to build 12 submarines in SA.

The pressure has been building, with SA MP Matt Williams saying his support for Mr Abbott depended on whether SA would get a significant share of the work.

Senator Edwards said in the case of a leadership ballot his vote would depend on SA being able to take part in a competitive tender, which is what most experts have recommended to Government.

Senator Edwards said he had been in regular contact with Mr Abbott to discuss the submarines and had urged new Defence Minister Kevin Andrews to think about what the money meant for SA jobs and the economy.

“I’m pleased to say the message has got through,” he said.

“I’m very pleased with the decision of the Prime Minister and when he rang me today with this very good news — it now commits the Government to a full and open tender — and this should lead to hat throwing, to punching the air.

“Now the work starts for Premier Jay Weatherill to get behind the Federal Government to provide the best capability for the Australian Navy.”

Opposition Leader Bill Shorten said that “it wasn’t the thousands of shipbuilding jobs at risk that forced Tony Abbott to act”.

“It was the threat of losing his own,” he said.