A former Liberal Democrat minister has warned that she intended to defy the party leadership and vote against coalition plans to cap benefits.
Sarah Teather, who lost her job as children and families minister in the September reshuffle, said she would oppose proposals to limit rises for most working age benefits to 1% when they come to the Commons on Tuesday.
She said: "As a constituency MP representing a very deprived area in London, I feel deeply anxious about the policy and I will be voting against the bill tomorrow, very reluctantly and with a very heavy heart. I can't say I enjoy voting against the Government on these things."
Her comments represent a further blow to Deputy Prime Minister Nick Clegg - particularly as they reflect concerns among many Lib Dem activists. She also echoed Labour in warning that the measures would hit many working families on low incomes as well as those without jobs.
"We have a huge problem with in-work child poverty and we are only going to make this significantly worse by affecting those who are at the bottom end of the income spectrum," she said.
Ms Teather also attacked the way Chancellor George Osborne and other Conservative ministers had sought to characterise benefits claimants as "scroungers" who were unwilling to work.
"One the the things I feel particularly uncomfortable about is the setting up of these two groups - the supposed strivers versus scroungers. It's playground politics. I don't think it is really worthy of us," she said.
"To try to set these two groups up and drive envy and division between them, I don't think is very helpful for the country and it is not very enlightening for debate."
Her comments came as the widely respected Institute for Fiscal Studies warned that the impact the cap on low income households would be even more severe if inflation turned out to be higher than predicted.
"There is an arbitrariness to this eventual outcome," it said in its latest analysis. "The actual effects of the bill on real benefit rates are unknown, because they depend on future price levels. This exposes the poorest in society to inflation risk."