The party has announced tonight that a Labour government will repeal the measure, which has already forced around  half of those tenants affected into rent arrears, a quarter of those for the first time ever. Significantly, rather than merely another policy that Labour would enact "were it in government now", this is a manifesto commitment.
The National Housing Federation and the National Audit Office have predicted that the measure could end up costing more than it saves by forcing social housing tenants into the more expensive private sector (due to the lack of one-bedroom council properties available) and by increasing rent arrears (which deprives councils of revenue). But in order to demonstrate their commitment to fiscal discipline, Miliband and Ed Balls have still outlined how they will raise the £470m the Treasury claims the measure will save this year.
Labour has said it will:
- Reverse the £150m tax cut for hedge funds announced in the 2013 Budget.
- Abolish George Osborne's "shares for rights " scheme, which businesses have been using to avoid capital gains tax (shares sold at a profit are exempt) and which the OBR has forecast could cost up to £1bn.
- Prevent construction firms avoiding tax by falsely listing workers as self-employed.
Miliband will say tomorrow:
One Nation Labour is meeting here in Brighton talking about the most important issue facing families in Britain: the cost of living crisis.
Under David Cameron life is getting harder and harder with prices rising faster than wages in 38 of the 39 months that he has been in Downing Street. And working people are an average of almost £1,500 a year worse off under his government.
But we have a Tory-led Government which listens only to a privileged few. Tax cuts for millionaires and tax breaks for hedge funds.
I am leading a different Labour Party, a One Nation Labour Party, which listens to and will stand up for ordinary families like that of Danielle Heard, who I met this week.
We’ll fight for her like she has fought cancer heroically for 14 years. She is disabled and battling cancer again. But now her family must pay £80 a month they can’t afford under this government’s hated bedroom tax.
The bedroom tax – not what the Tories call the spare room subsidy – the bedroom tax: a symbol of an out of touch, uncaring Tory government that stands up for the privileged few – but never for you.
So we will scrap that tax. And what’s more I can tell you how.
We’ll scrap the bedroom tax by abolishing the shady schemes of tax loopholes for the privileged few which the Tories keep inventing. Tax cuts for hedge funds, the billion pound black hole created with a scheme for workers to sell their rights for shares, and by tackling scams which cheat the taxpayer in construction.
That’s what a One Nation Labour government will do. That’s a party that will fight for you.
The Tories will respond by arguing that Labour has abandoned its commitment to fiscal responsibility and returned to its old spending ways. But unlike on other issues, such as the benefit cap, they find themselves on the wrong side of public opinion. A ComRes poll published today  by the National Housing Federation (NHF) found that 59% of the public believe the policy should be abandoned, up from 51% when it was introduced in April. Four-fifths of Labour supporters (79%) favour its repeal, along with 65% of Lib Dems and 34% of Tories.
And one doesn't have to look far for evidence why. As I noted, a survey  by the NHF of 51 housing associations found that more than half of those residents affected by the measure (32,432 people), fell into rent arrears between April and June, a quarter of those for the first time ever.
Ministers have defended the policy, which reduces housing benefit by 14% for those deemed to have one 'spare room" and by 25% for those with two or more, on the basis that it will encourage families to downsize to more "appropriately sized" accommodation. But they have ignored (or at least pretended to ignore) the lack of one bedroom houses available. In England, there are 180,000 social tenants "under-occupying" two bedroom houses but just 85,000 one bedroom properties available to move to. Rather than reducing overcrowding, the policy has largely become another welfare cut, further squeezing families already hit by the benefit cap, the 1% limit on benefit and tax credit increases (a real-terms cut) and the 10% reduction in council tax support.
The measure is also coming under increasing fire from the Lib Dems. Shirley Williams described it as "a big mistake" at the party's conference and delegates passed a motion calling for "an immediate evaluation of the impact of the policy, establishing the extent to which larger homes are freed up, money saved, costs of implementation, the impact on vulnerable tenants, and the impact on the private rented sector." It also called for "a redrafting of clear housing needs guidelines in association with those representing vulnerable groups including the disabled, elderly and children."
Whether or not the coalition eventually goes as far as scrapping the measure, to prevent Labour surfing a wave of public outrage, it is hard to see it surviving in its current form.