A cross-party group of MPs and peers have called on the main parties to make a manifesto pledge not to allow the UK's population to exceed 70 million.
Former minister Frank Field is among those arguing current immigration rates, unless restricted, will impact on public services and quality of life.
All the main parties are sceptical about setting population targets which they believe is unrealistic and counter-productive.
Last year the Office for National Statistics said if current trends continued, the UK population would rise by 10 million to more than 71.6 million by 2033 - the fastest rise in a century.
Two-thirds of that increase would be caused, directly or indirectly, by migration to the UK, it suggested.
'Social harmony'
Nearly 20 parliamentarians, including five Labour MPs and 10 Conservative MPs, are backing a campaign calling for curbs on immigration entitled "70 million is too many".
Current levels of immigration into the UK were "unprecedented", it said, and threatened the "future harmony of our society".
"Poll after poll shows the public to be deeply concerned about immigration and its impact on our population," Mr Field and Tory MP Nicholas Soames, the group's co-chairmen, said.
"It is time parties turned their rhetoric into reality by making manifesto commitments to prevent our population reaching 70 million by 2029."
For a start, they argue, the government must "restore control" over the UK's borders and "break the present almost automatic link between coming to Britain and later gaining citizenship".
Net migration - the number of people who come to live in Britain minus those who leave - fell by more than a third in 2008 but critics say this was driven by eastern Europeans returning home and immigration levels must fall to levels of the early 1990s.
Official estimates that the UK population will pass 70 million by 2025 were based on a forward projection of the 2007 net migration figure and this is likely to be revised downwards in light of the 2008 figures.
Popular Alliance Comment:
Britain is full and has been for ages. We cannot allow our services and taxes to be used up on uncontrolled immigration whilst we allow millions of home born Britains to be out of work whether that be through choice or not. A strict cap is needed on both EU and Non- EU immigrants. We should re-negotiate that part of EU policy as soon as possible.
