Sir Sadiq Khan tore into Sir Keir Starmer’s planned benefit cuts warning that “for too many disabled Londoners it will destroy their financial safety net”.
The London Mayor joined the growing revolt against the Government’s proposed welfare reforms just hours after the Prime Minister vowed to press ahead with them.
Some134 MPs - including about 120 Labour members - are now backing an amendment that threatens the PM’s cuts.
Sir Sadiq said: “I have always said that more must be done to support people to go from relying on benefits to getting back into work. It’s vital for a healthy and prosperous London.”
However, he added: “What we can’t do is take away the vital safety net that so many vulnerable and disabled Londoners rely upon.
“Having looked at the analysis of the Government’s plans, the impact on London will be substantial, and for too many disabled Londoners it will destroy their financial safety net.”
City Hall said that analysis had shown that Londoners will lose £820 million in total as a result of the proposed changes to Personal Independence Payment (Pip) and Universal Credit, with 360,000 mostly poor, vulnerable and disabled Londoners facing a reduction in their incomes.
It added that tighter eligibility criteria for Pip will affect up to 46 per cent of current claimants and mean disabled Londoners face losses of between £3,800 and £5,700 per year
The Mayor’s intervention came as Sir Keir was risking a major Commons defeat as he refused to change his welfare reform plans despite about 120 Labour MPs threatening to rebel against them.
The Prime Minister insisted there was a “moral case” for the reforms which have sparked anger and disquiet among Labour backbenchers and ministers.
In an intervention on Tuesday evening Tory leader Kemi Badenoch offered to save the Prime Minister’s reforms in the face of the rebellion as she offered to lend support from Conservative MPs to his Welfare Bill to get it through Parliament, a move that would outrage Labour MPs.
She said:“The government is in a mess, their MPs are in open rebellion. If Keir Starmer wants our support, he needs to meet three conditions that align with our core Conservative principles.
“The first condition is that the welfare budget is too high, it needs to come down. This bill does not do that.
“The second condition is that we need to get people back into work. Unemployment is rising, jobs are disappearing, and even the government’s own impact assessments say that the package in this bill will not get people back to work.
“The third is that we want to see no new tax rises in the autumn. We can’t have new tax rises to pay for the increases in welfare and other government spending.
“We are acting in the national interest to make the changes the country needs. And if Keir Starmer wants us to help him get this bill through, then he must commit to these three conditions at the dispatch box.”
Earlier senior London Labour MP Dame Meg Hillier, who is at the helm of the revolt, urged Sir Keir to “listen” to the rebels rather than end up being defeated in a showdown Commons vote next week.
The PM, though, was defiant in the face of the looming revolt.
"The welfare system is broken and that's why we will press ahead with our reforms,” he said, speaking in the Netherlands where he was attending a Nato summit in The Hague
"People are trapped in it and I'm not prepared to allow that to happen."
He emphasised that there was "a clear moral case" for the changes, with 1,000 people per day going onto Personal Independence Payments (Pip).
Sir Keir said: "The additions to Pip each year are the equivalent of the population of a city the size of Leicester.
"That's not a system that can be left unreformed, not least because it's unsustainable and therefore you won't have a welfare system for those that need it in the future."
But Dame Meg, MP for Hackney South and Shoreditch and who chairs the Commons Treasury Committee and Commons Liaison Committee, urged the PM to reconsider the proposals after more than 100 Labour MPs signed a rebel amendment to block them.
“The system needs reform. The challenge and the problem is how it is being implemented,” she told BBC radio.
She branded the reforms as “very confusing” and voiced “surprise” that the Government had not been more receptive to consider changes.
“I hope the Government will listen to this groundswell of opinion,” she added.
Fifteen London MPs have joined the major revolt against Sir Keir’s welfare cuts in the biggest showdown for the Prime Minister since taking office nearly a year ago.
The rebel amendment, published on Tuesday’s order paper, notes there is a “need for the reform of the social security system”.
But it calls for the Commons to decline to continue scrutinising the Universal Credit and Personal Independence Payment Bill “because the Government’s own impact assessment estimates that 250,000 people will be pushed into poverty as a result of these provisions, including 50,000 children”.
There has been no formal consultation with disabled people who will be impacted by the changes, the MPs added.
They also point to the fact that an analysis of the impact of the reforms on jobs from the Office for Budget Responsibility will not be published until the autumn.
London Labour MPs who have put their name to the amendment include Dame Meg, Florence Eshalomi (Vauxhall and Camberwell Green) who chairs the Housing, Communities and Local Government Committee, Ruth Cadbury (Brentford and Isleworth) who chairs the Transport Committee, Vicky Foxcroft (Lewisham North), the former Government whip who resigned over the welfare plans, and Diane Abbott (Hackney North and Stoke Newington).
The other Labour MPs in the capital who have signed it are Helen Hayes (Dulwich and West Norwood), Dawn Butler (Brent East), Clive Efford (Eltham and Chislehurst), Bell Ribeiro-Addy (Clapham and Brixton Hill), Stella Creasy (Walthamstow), Marsha De Cordova (Battersea), Kate Osamor (Edmonton and Winchmore Hill) and Rosena Allin-Khan (Tooting).
John McDonnell (Hayes and Harlington) and Apsana Begum (Poplar and Limehouse), who are both independent MPs having lost the Labour whip for voting against the two-child benefit cap, are also backing the amendment.
The rebellion, the Prime Minister’s largest yet, would be enough to defeat the Government’s plans if opposition MPs joined the Labour rebels.
