The Conservatives have attacked Labour's proposal to cap private sector rent rises a "short-term gimmick".
Tory chairman Grant Shapps also claimed the policy was inspired by the leader the Unite trade union, Len McCluskey.
“Evidence from Britain and around the world conclusively demonstrates that rent controls lead to poorer quality accommodation, fewer homes being rented and ultimately higher rents – hurting those most in need," Mr Shapps said.
"And it’s yet another Labour policy bought by Ed Miliband’s union boss, Len McCluskey.
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