The Government is coming under increasing pressure to help end uncertainty over the future of thousands of elderly residents and staff at Britain's largest care homes group.
Southern Cross, responsible for looking after 31,000 elderly residents, has announced that it will underpay its rent as it struggles with a £230 million annual rental bill.
The firm, which owns almost 750 care homes and employs thousands of staff, will pay nearly a third less rent than it is obliged to for the next four months in what is effectively a loan from its landlords.
GMB general secretary Paul Kenny said: "The focus now has to be on what happens to the 31,000 elderly and vulnerable residents in Southern Cross homes across the UK.
"The GMB is calling on politicians across the country to step in and sort out the uncertainty that surrounds the future of these care homes. These are not factories facing closure, they are a vital part of the social fabric of every community."
Southern Cross chairman Christopher Fisher said: "We believe that all of the key stakeholders in Southern Cross want this restructuring to succeed. We are in dialogue with the Department of Health, our lenders and landlords and they continue to support the process."
Prime Minister David Cameron's official spokesman gave a guarantee that affected residents would not "lose out" in the process.
"We are clear that we are putting the interests of residents at the top of the list," he said. "It may well be in their interests to keep them in the same place.
"But I think we have to look at that very carefully and we have got to let this process continue with the company and the various other interested parties. Our interest is to make sure these people are cared for effectively."
Asked if residents could take that as a guarantee that they would not lose out, he said: "Exactly right".