Work and Pensions Secretary Liz Kendall has launched a charm offensive to win over Labour MPs furious over new limits on disability benefits. Ministers and officials from her department are holding talks with backbenchers in advance of a vote expected on July 1.

Sir Keir Starmer’s political director, Claire Reynolds, has also met potential rebels. Party whips have reportedly urged backbenchers unable to support the changes to stay away from the vote entirely rather than vote against. It is thought up to 80 MPs could rebel, although many of the most vocal opponents are Left-wingers and it is unclear how many backbenchers from other sections of the party will join them.

Merseyside Labour MP Ian Byrne urged colleagues to oppose the changes when they are introduced as part of the Universal Credit and Personal Independence Payment (PIP) Bill. He said: “This Bill will bring forward the most devastating cuts to disability benefits on record.

“The Government’s own impact assessment report says 250,000 people could be pushed into poverty. This Bill, if passed, will be a stain on the Labour Party for years to come. I urge Labour MPs to reject it.”

Middlesbrough Labour MP Andy McDonald said: “This Bill will be a yes or no on impoverishing disabled people. It’s a no from me.”

New rules making it harder to claim PIP, which helps disabled people with living costs, will save the Treasury £4.1billion a year but will mean 800,000 people lose an average of £4,500 annually. The Government’s own analysis shows there will be an extra 250,000 people in poverty, including 50,000 children, as a result of benefit changes already announced.

In addition, changes to Universal Credit are expected to affect an estimated 2.25million current recipients of the health element, with an average loss of £500 per year.

But the Government said about 3.9million households not on the Universal Credit health element are expected to make an average annual gain of £265 from the increase in the standard allowance.

Ms Kendall said the legislation “marks the moment we take the road of compassion, opportunity and dignity”.

She added: “Our social security system is at a crossroads. Unless we reform it, more people will be denied opportunities, and it may not be there for those who need it.”

In what could be seen as an attempt to head off some opposition, the legislation will give existing claimants a 13-week period of financial support.

The Department for Work and Pensions said this will apply to those affected by changes to the PIP daily living component, including those who lose their eligibility to Carers Allowance and the carer’s element of Universal Credit.

But campaigners, including disability equality charity Scope, said the longer transition period, up from an originally expected four weeks, “will only temporarily delay a cut and disabled people will continue to be living with extra costs when it comes to an end”.

The Bill was formally introduced to the Commons on Wednesday. As the next date for debate on the Bill was discussed, former Labour MP John McDonnell, who now sits as an independent for Hayes and Harlington, could be heard to say: “Never.”

While all of the Bill applies to England and Wales, only the Universal Credit changes apply to Scotland.