Workers at the Ford factory in Bridgend are to vote on whether to take industrial action as they fight to save their jobs and the future of the plant.
Unite has confirmed a ballot will be held in May with the result expected at the end of the month.
A union spokesman said: "Members say there is a strong resolve to take some form of industrial action."
Ford called the ballot "premature" and said it remained committed to "on-going constructive dialogue" with unions.
Unions said in March the plant could potentially lose 1,160 jobs.
The spokesman said the decision to vote on industrial action followed a consultative ballot.
He said workers did not have to take strike action, they could choose industrial action that falls short of an all-out strike.
Talks would continue with Ford about the future of work in Bridgend.
"We hope those talks will be positive," he said. "We are not on a mission to take the company on, we want to work together."
A Ford spokesman said: "As we have consistently stated, Ford remains committed to on-going constructive dialogue with our union partners and we have proposed a dedicated work stream to examine future business opportunities for the Bridgend operation.
"We consider any ballot for industrial action to be premature given that the opportunity for productive engagement, in line with established employee relations and working practices, has been and continues to be readily available."