Coalition plans to cut payments to families with disabled children have been rejected by the House of Lords in a seventh defeat for Iain Duncan Smith's welfare reforms.
In another embarrassing blow to the Welfare Reform Bill, peers voted by 246 votes to 230, majority 16, against the move.
They backed an amendment by independent crossbench peer Baroness Meacher to limit cuts to top-up payments made to the parents of disabled children.
The Government wants to introduce a slight increase to the weekly rate for the most disabled children, taking it to £77, while halving the lower rate to £27.
Ministers argue the money saved will be spent on providing additional support to the most disabled adults.
But Lady Meacher said the Government's plans would mean families with a child on the lower rate losing £1,400 a year. Her successful amendment specifies that the lower rate must be at least two-thirds of the higher rate.
She said the Government aimed for the proposals to be "revenue neutral" and told peers: "The proposition here is that ministers revisit the relationship between the new levels of disability addition for children and allocate resources to adults when new money allows."
She warned that there would be a "cliff edge" between the two levels of the benefit and said there were children who were "very severely disabled" who would not qualify for the higher amount.
This is the seventh defeat peers have inflicted on the Bill, but it later cleared the Lords. It will return to the Commons on Wednesday where MPs are expected to overturn many, if not all, of the defeats, which will result in a potential stand-off with peers.
A Department for Work and Pensions spokesman said: "The present system of disability support is a tangled mess of premiums and add-ons which is highly prone to error and baffling for people to understand. Under our reforms, support will be focused on the most severely disabled people. It will create a simpler and fairer system and transitional protection will ensure that people will not receive less as a result of their move to universal credit - where circumstances remain the same."