Minister Grant Shapps has said people will not be "chased out of their homes" by reforms to social housing in England which could end council homes for life.
Ministers want to allow councils and housing associations to grant fixed term tenancies lasting at least two years for new tenants.
Mr Shapps said the vulnerable would be protected and councils could still grant tenancies for life.
But he said with five million people on the waiting list, change was needed.
The Department of Communities and Local Government has published a consultation document outlining plans to reform social housing in England - which include the option of shorter tenancies, as well as allowing social landlords to charge a higher rent for shorter term tenancies - of up to 80% of local market rents.
It also allows councils to set the rules for who qualifies for the housing waiting list - although central government will still set rules for who gets priority - and introduces a new "social home swap scheme" for tenants who want to move areas.
Other proposals include allowing councils to offer those made homeless private rented housing and introducing a new "self financing arrangement" for council houses.
Existing tenants would not be affected by the proposals.
Mr Shapps told BBC Radio 4's Today programme the housing waiting list had doubled in the past 13 years and would double again if nothing was done: "The whole point of this is to ensure that we can actually house more people and in appropriate sized homes for each individual."
The document says that new fixed term tenancies would have "a minimum time period of at least two years but no maximum time period".
When a fixed term tenancy came to an end, landlords would decide whether to reissue it, reflecting the "tenants' levels of continuing need, work incentives and local pressures for social housing".
It says the government will decide after consultation whether the minimum period should be longer, "whether some groups should always be guaranteed a longer fixed term or a social home for life and whether existing secure or assured tenants should always continue to receive a lifetime tenancy when they move".
The possibility that tenants may only get two years in a property - with six months' notice from landlords - has worried some housing charities.
Campbell Robb, chief executive of Shelter, said: "We know that very few people go from homeless to self-sufficient within two years. The proposal... shows the government's naivety in how quickly people are able to get back on their feet, and we urge them to reconsider this in favour of at least a five-year minimum."
Mr Shapps told the BBC the fixed term tenancies would be "significantly more protected than the private rented sector".
"There's no reason why a home in future should always be the home for life. You don't get that in the private sector," he said.
He said most tenancies were likely to be of "significant length" - of between five years and a lifetime.
"All of the kind of statutory rules will be in place to ensure that the most vulnerable are protected and people are not being chased out of their homes in any way. We just need a more flexible system."
The measure will be subject to consultation, but the government hopes it will be in place by summer 2011.
Lib Dem Deputy Leader Simon Hughes said his party would need "a lot of persuading" when David Cameron first mooted the idea of ending life-long tenancies in the summer.
For Labour, shadow housing minister Alison Seabeck said: "The government's plans will worry both existing and prospective social housing tenants up and down the country.
"Council tenants are being told they may be forced to move if their income increases. That sends the wrong message to families trying to get on and could act as a cap on aspiration."
The coalition has announced plans to cut funding for social housing by more than 60% and for new tenants to pay higher rents but says it hopes the changes would free up funds to build 150,000 new affordable homes over the next four years.
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