Boeing bosses have responded viciously to efforts by Washington's aircraft engineers' efforts to preserve their pension scheme.

They made good on previous threats and began looking elsewhere on Thursday to develop Boeing's new 777X aircraft.

A spokesman for Utah governor Gary Herbert said Boeing officials had called him to begin talks that could export the work - and thousands of jobs - to that state.

Boeing spokesman Doug Alder said there were many places both within and outside Boeing's current operations being explored.

"Everything is back on the table," he said.

In 2003, Washington state approved a package of tax breaks for Boeing in hopes of securing long-term work from the company.

But Washington state leader on aerospace Alex Pietsch said that he expected competition for the 777X from across the US.

In the contract vote late on Wednesday, the International Association of Machinists District 751 had rejected company proposals with 67 per cent of the votes.

Union members voted in protest against Boeing's push to end their traditional pension plan and increase their healthcare costs.

The company was attempting to capitalise on the long-term stability expected with the 777X by forcing concessions on the engineers, sugaring the pill with a $10,000 (£6,200) bonus if they approved the deal.

But the machinists thought differently.

"We preserved something sacred by rejecting the Boeing proposal.

"We've held on to our pensions and that's big.

"At a time when financial planners are talking about a retirement crisis in America, we have preserved a tool that will help our members retire with comfort and dignity," said District 751 president Tom Wroblewski on Wedneday night.

Washington had even hurried through a $9 billion (£5.5bn) extension of tax breaks and money to improve training programmes, but apparently to no avail.

Boeing expects tax breaks, easy permit approvals, port, rail and road infrastructure and even free land as an incentive and some taxpayer groups warn the cost of incentives can amount to $500,000 (£310,000) per job.

Washington will try to bring the union and Boeing back together for more talks next week, Mr Pietsch said.