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.
More top news
Almost 20,000 hand-made shrouded figures have been laid out to mark the 100th anniversary of the Battle of the Somme.
Jeremy Corbyn has come under fire in a fresh row over Israel after he appeared to compare the Israeli state to jihadi terrorists.
Thousands of soldiers who died in the Battle of the Somme will be remembered today at commemoration events across the UK and France.