Mortgage providers are warning of a £300bn shortfall in the amount they will be able to lend which will not be filled by savers' deposits.
The funding gap is currently being filled by government schemes, but these will end in 2014, the Council of Mortgage Lenders (CML) said.
In the long-term, this could reduce choice for consumers.
It could also hit first-time buyers, as loans would be restricted to those who could offer a large deposit.
"The UK [could be] at risk of a chronic under-supply of credit - and the rationing of mortgages for customers - for many years to come," the CML said, in its News and Views publication.
Credit crunch
The funding gap was previously covered by the wholesale mortgage debt market, the CML said.
But this froze at the start of the credit crunch in 2007, forcing the government to fill the void with programmes such as the special liquidity scheme and the credit guarantee scheme.
The CML fears that the wholesale markets will not return to the levels seen before the credit crunch, and the gap will not be filled by retail deposits from savers.
"Unless there is a policy approach intended to encourage the development of wholesale funding, we are likely to see a long-term decline in choice for UK mortgage customers," the CML said.
It added that a "clear strategy" was needed to put the UK mortgage markets back on a "sustainable footing" immediately after the general election.
