Jonathan Isaby from the TaxPayers' Alliance said taxpayers would "resent" paying for spare rooms for those receiving housing benefits "when they can't have one themselves."
He said: "I'm not saying that there aren't people who do need those rooms but you can't have a blanket exemption for hundreds and thousands of people."
Campaigners against the Government's so-called 'bedroom tax' will take to the streets tomorrow in protest of the proposals.
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Rain will be heavy across Scotland, parts of northern England and Wales tonight - rumbles of thunder are possible waking some of us up.
A report out tomorrow shows energy bills are 5% higher than they should be costing Brits as much as £1.2 billion a year.
Caroline Wozniacki has sparked a sexism row at Wimbledon after saying women do not feature enough on the major courts.