Just 6% of tenants affected have moved but the measure is saving money.
The party's conference voted overwhelmingly that it was the wrong thing to do, but does that get across to the average voter?
A source close to the Lib Dem president says he will vote against the government after party members "expressed their will very strongly against the Bedroom Tax".
The punitive penalty presents appalling dilemmas for vulnerable families. Ministers should finally accept that they have lost the argument.
The rebel Lib Dem says the policy is "Dickensian in its social divisiveness" and "victimises the most marginalised".
The party's announcement that it will hold a Commons vote next Tuesday on scrapping the measure is a test of those in Clegg's party who have condemned it.
In its determination not to refer to the "bedroom tax", the party mistakenly claims that Labour is "opposed" to the "spare room subsidy".
For the vast majority of those affected, there is nowhere smaller to move to, leaving vulnerable people hit with extra costs through no fault of their own.
Labour leader announces: "We’ll scrap the bedroom tax by abolishing the shady schemes of tax loopholes for the privileged few which the Tories keep inventing."
As Labour prepares to promise to repeal the measure, a new survey finds that 59% want to see it scrapped.