Plans by General Electric to cut 1,100 jobs at its Staffordshire and Warwickshire bases have been described by unions as a "major blow to the Midlands".
The cuts, which will be split evenly between sites in Stafford and Rugby, were announced in response to waning demand for fossil fuel power.
The proposals include the closure of the Lichfield Road factory in Stafford.
The US industrial group said it remains committed to the UK.
'Bolt from blue'
Zoe Mayhew, the regional officer for the union Unite, said workers had been left "bewildered" by the news.
"This is a bolt from the blue for many people," she said. "Before Christmas is never a good time."
She said the site in Rugby was "part of the furniture" in the town.
"It's been here for years," she said. "Generations have worked here. The people of Rugby will come together to fight this."
The town's Conservative MP Mark Pawsey said the announcement was of "real concern".
"There will, of course, be a consultation period and I am confident the workforce will make a strong and compelling case for Rugby."
The announcement was made at lunchtime when some workers at the Stafford site told the BBC they had not heard the news.
One worker said: "I have just come from an off-site meeting so I'm about to find out [about it]."
The company is the town's largest private employer. The factory being considered for closure makes industrial-scale electrical equipment.
"There are a lot of skilled workers that are going to be out of a job now with no further industry in Stafford for them to go into," said one employee.
Stafford's Conservative MP Jeremy Lefroy said he was "very disappointed".
"I will be working extremely closely with the government, the company and staff to see what can be done to mitigate the effect of this announcement," he said.
Staffordshire County Council's economic growth leader Mark Winnington described the news as "devastating".
Unite national officer Linda McCulloch said the proposals "deal a major blow to the Midlands' economy which will be deprived of highly-skilled, well-paid jobs."