The prime minister said there was a “clear moral case” for the reforms, which aim to slash £5bn a year from the welfare bill by 2030.
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While many Labour MPs initially indicated they backed the bill in principle, support has ebbed away over recent months amid warnings about the impact the cuts could have on the most vulnerable people in society.
Around 119 Labour MPs have now signed a reasoned amendment to oppose the government’s proposals – which, if passed, would effectively kill the legislation.
But speaking to Sky News’ political editor Beth Rigby from the NATO summit at the Hague, the prime minister said the welfare system needed reform and was “not working for anyone”.
He said the vote planned for Tuesday was not a confidence vote in his leadership but on the need to reform the system.
“I think most colleagues do accept the case for reform,” he said.
“We’ve got to get on and make that reform because the options are: leave the system as it is, trusting people and not helping them, that’s not a Labour option. The Labour option is to reform it and make it fit for the future. So we’re going to press ahead with these reforms.”
Welfare system ‘unsustainable’
Sir Keir spoke to reporters on the way to the summit about the reforms, saying there were around 1,000 people a day signing up for personal independence payment (PIP) – equivalent to the size of the population of Leicester.
“That is 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,” he added.
“So those that care about a future welfare system have to answer the question – how do you reform what you’ve got to make sure it’s sustainable for the future?'”
Introduced in March, the government’s welfare bill outlines proposals to make it harder for some disabled people to qualify for PIP while also cutting universal credit, another benefit.
The reasoned amendment calls on the government to delay the proposals pending an assessment of the impact of the PIP cuts.
It also cites concern about the government’s own figures which show 250,000 people could be pushed into poverty as a result of the changes and the lack of a formal consultation with disabled people.
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One Labour rebel told Sky News there was a “broad sense of unease across all levels of the parliamentary party”.
“Almost everyone thinks there needs to be reform and there are a lot of good things in the bill, but elements need more thought and explanation if they are going to proceed,” they said.
“Unless those issues are revised, or much better explained and justified, I don’t think there is enough support for the measures. People are really worried there is a rush to do this and that we might sleepwalk into this as we have done with other issues.”
On Tuesday, Downing Street suggested the vote would still go ahead despite the concerns of some MPs – including influential chairs of parliamentary select committees.
Asked whether the government was confident it could pass the legislation, a Number 10 spokesman told reporters: “We are focused on delivering last week’s bill and engaging, talking to colleagues, as to why this reform is so important.”
Pressed on whether the vote was happening next week, they added: “I would never get ahead of parliamentary business. It’s scheduled for next week. We are committed to reforming welfare.”
