Southern Cross, which looks after 31,000 elderly people across the UK, is in talks with the government over its financial difficulties
The government said it would work with local authorities to ensure people in 750-plus homes were protected.
Southern Cross said it was seeking "concessions on our rent bill".
Paul Burstow MP, care services minister at the Department of Health, said officials were "in communication with the Association of Directors of Adult Social Services regarding their responsibilities and their contingency plans should the situation develop".
Care Services Minister Paul Burstow said: "Southern Cross has had discussions with government officials about the plans they have in place to address their financial difficulties and ensure that service and quality are maintained."
On 14 March, the Southern Cross said that national budget cuts meant its rent burden was "unsustainable".
Pam Finnis, regional director central, Southern Cross Healthcare, said: "We have an important role to play in delivering front line services to care for elderly people across the UK.
"We are taking decisive action to ensure our business remains sustainable.
"We are also urging government, landlords and commissioners to work co-operatively in supporting us."
Councils across the country are looking at how to protect elderly people at the homes.'Safety vital'
Essex County Council, which has 23 Southern Cross care homes, said it was "committed to ensuring the safety of all vulnerable people in Essex, and is continuing to work closely with Southern Cross to ensure the continuity of services".
A spokeswoman from Northamptonshire County Council, which has six Southern Cross care homes, said the authority is looking at "what emergency measures we would potentially have to take to ensure the welfare of vulnerable people affected".
Harold Bodmer, director of community services at Norfolk County Council (which covers 15 Southern Cross homes), said: "There is as yet no indication that Southern Cross will not be able to continue to provide a high quality of care for the residents in their care homes.
"But, should the situation change, we have plans in place to ensure that the care needs of those people for whom we are responsible are met."
Shaun Graham, senior organiser with union GMB which represents 10,000 workers in the homes, said: "We want to ask what exactly the contingency plans are if Southern Cross and the Government fail to cut the rents and Southern Cross has to go into administration."