David Cameron's plans to end council housing "for life" could act as a disincentive for tenants to get better-paid work, a Tory backbencher has said.
The PM has suggested tenants in England should get fixed-term contracts and be moved on if their finances improve.
But Nadine Dorries, Mid-Bedfordshire MP, said she did not believe it would help social housing shortages.
Lib Dem deputy leader Simon Hughes has already said his party is against the idea, which is not coalition policy.
Mr Cameron had suggested greater flexibility was required within the social housing system, allowing tenants to move to find work.
He said homes should be allocated according to need in future, with people moving into private sector accommodation when their circumstances improved rather than being allowed to remain in a home for life and even - in some cases - pass it to their children.
However, Ms Dorries told BBC Radio 4's Today programme: "We have 1.8 million people who need council houses now. I don't see that reviewing new council house tenants in five years and if their situation has improved moving them on, is going to do anything to deal with the problem we have today.
"The bedrock of families is the family home and I do not think that saying to people 'in five years' time you might lose your home' is a good way for people to try to improve their lot.
"Rather than saying to people 'if your lot has improved you will be moved on' we should be giving the option to buy. That incentivises people to improve their lot."
She suggested that the government could prevent further reduction in the supply of affordable housing by asking taxpayer-backed banks to find ways to finance the construction of replacement homes.
Labour says council tenants need long-term security and that more social housing is needed.