The relationship between the Tories and Lib Dem's is under increasing pressure after Nick Clegg changed tack on 'bedroom tax'.
After a committee of MPs said the bedroom tax unfairly affects disabled people, Tim Farron says his party will push for change.
The mother of a disabled child described how she struggles to make ends meet after having her housing benefit cut by 14%.
Almost 60% of households affected by the "bedroom tax" changes were in arrears as a result of the cut to their housing benefit, an internal Government review has found.
Under the policy, social tenants deemed to have a spare room see their rent eligible for housing benefit reduced by 14%, rising to 25% if they have two or more extra bedrooms.
Some 20% of those affected had paid none of the shortfall and 39% had only paid their landlords part of the money owed, the interim report for the Department for Work and Pensions (DWP) found.
The report found 522,905 households were affected by the policy in August 2013, which equates to 11.1% of social tenancies. Some 57% of claimants were cutting back on household essentials and 35% on non-essentials in order to pay their shortfall.
The grandparents of a severely disabled teenager have lost their legal challenge against the so-called "bedroom tax".
Paul and Susan Rutherford, from Pembrokeshire, are full-time carers to 13-year-old Warren, who suffers from a rare genetic disorder which means he is unable to walk or talk and cannot feed himself.
The case concerned regulations, introduced in April 2013, which have led to reductions in housing benefit payments to tenants in social housing assessed through controversial "size criteria" to be under-occupying their accommodation.
Mr Justice Stuart-Smith, at London's High Court, rejected their challenge to the lawfulness of the regulations and dismissed the application for judicial review.
A father of a disabled boy who will have to pay money back under the "bedroom tax" has hit out at the "dreadful" scheme.
Jimmy Daly from Stoke told Daybreak he was moved into his current two-bedroom home to help him cope with his son's disabilities, but because his son does not live with him full time, Jim has to pay some money back.
"I was moved in here because of his disabilities, and now they're saying because your son is disabled you have to pay this dreadful tax. It's wrong."
The bedroom tax has been "mismanaged from the start" and has failed to free up larger properties, according to Labour.
Shadow welfare minister Chris Bryant said:
– Chris Bryant
This ill-conceived policy has been mismanaged from the start.
It's failed to free up larger properties because there simply aren't smaller properties to move to.
It's hitting the most vulnerable hardest, and failing to save the money that David Cameron had predicted.
The Government has no reason to keep it - if they won't repeal it, a Labour government will.
The bedroom tax has failed to save the taxpayer £115 million of the £445 million that was expected, a leading social policy charity has found.
A report by the Joseph Rowntree Foundation said savings from the so-called bedroom tax - a reduction in housing benefit for social housing tenants deemed to have more rooms than they need - were lower than expected but fewer people had been affected.
Around 498,000 people had been affected altogether, the report said, compared with an initial Government estimate of 660.000.
Report author Steve Wilcox said: "There are options to alleviate the worst effects of the policy - particularly in the provisions for people with disabilities, bedrooms too small to share, and those unable to move.
"The savings from the size criteria are modest, and will decline over time, but they have been achieved at disproportionate costs for tenants and landlords."
The Liberal Democrats wants to see the so-called 'bedroom tax' changed so that people do not face moving out of their home with nowhere to go, the party's president has told ITV News.
Current policy means social housing tenants who have a spare room face having their housing benefit reduced.
Speaking to Deputy Political Editor Chris Ship, Tim Farron said Nick Clegg shared "the view that this is something that we want to see changed".
Citizens Advice has said an extra room "can be a lifeline" for a disabled person, calling it "as vital as a guide dog or a wheelchair".
Chief executive Gillian Guy said for many people a spare room "is essential to their wellbeing" as it is needed for dialysis equipment or room for a carer.
Ms Guy said: "Many sick and disabled people have bedrooms which have been adapted to help them to cope with their condition.
"Moving disabled people out of their houses is not only a potential risk to their health, but can cost the individuals affected and councils significant amounts of money if they need to start from scratch in a new home."
The head of homeless charity Crisis has said the Government risks forcing poor people out of their homes because of changes to housing benefit such as the 'Bedroom Tax'.
– Leslie Morphy, Chief Executive of Crisis
"The Government must listen to this verdict from MPs across the political spectrum and rethink its cuts to Housing Benefit, particularly for those who cannot change their circumstances by working or who are struggling in low paid jobs. Without prompt action, the Government risks driving homelessness still higher."
Shadow work and pensions secretary Rachel Reeves said it was "completely unfair" that many disabled people were hit by the "bedroom tax" and charged for the space used to store essential medical equipment.
"Britain can't afford another year of David Cameron and Nick Clegg's tax on bedrooms," Ms Reeves said.
"If they won't listen to the country and scrap their hated bedroom tax, then a Labour government will," she added.