The Cabinet has backed Boris Johnson’s plans to reform health and social care funding, even though they are expected to involve a manifesto commitment-busting tax rise.

The Prime Minister will set out in the Commons later how he aims to tackle the social care crisis in England, with the risk of a Tory backlash if he raises National Insurance to pay for the reforms.

The tax hike, thought to be about 1.25 percentage points, will raise around £10 billion, which will be spent on the NHS as it recovers from the Covid-19 pandemic as well as to help people avoid crippling adult social care costs.

Ministers, who had been largely kept in the dark about details of the proposals, were briefed during the first in-person Cabinet meeting held in Downing Street this year.

The Prime Minister’s official spokesman said: “The Cabinet agreed to the proposals set out.

“There was strong agreement that this is a long-standing issue, particularly on the social care side, which had been ducked for too long and which needed to be addressed.”

Mr Johnson, Chancellor Rishi Sunak and Health Secretary Sajid Javid updated Cabinet ministers on the package.

The Prime Minister’s official spokesman said they set out the plan to tackle Covid backlogs in the health system, reform adult social care and “bring the health and social care systems closer together on a long-term sustainable footing”.

The spokesman said: “Cabinet agreed the challenges faced by our NHS and care sector are closely linked, and a lack of integration means people are often stuck in the wrong care setting.

“The Prime Minister highlighted that under the current care system, anyone with assets over £23,350 pays for their care in full, which can lead to spiralling costs with around one in seven people now paying over £100,000.

“The Prime Minister said that the changes he will announce today will fix this problem, which is causing chronic and unfair anxiety for millions of people up and down the country.”

Under current arrangements, anyone with assets over £23,350 pays for their care in full, but No 10 said the costs were “catastrophic and often unpredictable”.

Ahead of his Commons statement, Mr Johnson said: “We must act now to ensure the health and care system has the long-term funding it needs to continue fighting Covid and start tackling the backlogs, and end the injustice of catastrophic costs for social care.

“My Government will not duck the tough decisions needed to get NHS patients the treatment they need and to fix our broken social care system.”

After presenting his plans to the Cabinet, Mr Johnson could face a hostile reception in the Commons, with Labour and Tory MPs concerned about the impact of a rise in National Insurance contributions, which will hit workers but leave sometimes-wealthy pensioners untouched.

Finally, Mr Johnson, along with Chancellor Rishi Sunak and Health Secretary Sajid Javid, will attempt to sell the plan to the public in a Downing Street press conference.

Reports have suggested that lifetime contributions on care will be capped at about £80,000, and National Insurance will be increased by 1.25 percentage points to raise between £10 billion and £11 billion per year.

Ahead of the announcement, No 10 remained tight-lipped on the detail, but it has been reported the proposals will be called a health and social care levy.

Vaccines minister Nadhim Zahawi told Sky News that while he wanted to meet every manifesto commitment, the UK economy had gone through an “unprecedented shock” after the coronavirus pandemic.

Asked on Sky News whether he was “comfortable” breaking the 2019 manifesto commitment, he said: “I want to meet every single manifesto promise that we make, that’s the right thing to do.

“We have gone through an unprecedented shock to the economy because of the global pandemic and we’ve had to deal with it and make some really tough decisions.”

In a further sign of Tory discontent, former Conservative leader Sir Iain Duncan Smith told The Telegraph the plans were a “sham” because they did not reform the social care system while the newspaper also reported the Government was considering holding a snap vote in the Commons this week on the proposals.

The Guardian reported a Conservative frontbencher was considering their position over the plans.

Shadow health secretary Jonathan Ashworth said: “A long-term plan on social care and a rescue plan to address the crisis the NHS has been in for years are both long overdue.

“The Prime Minister must set out how he will bring down waiting lists quickly, support the NHS workforce, fix crumbling hospitals and deliver modern equipment to speed up diagnosis of deadly diseases and, crucially, ensure more people can access the social care they need.”

The changes would only apply in England, as Scotland, Wales and Northern Ireland have separate arrangements for social care.

It is not yet clear how any national insurance rise would be dealt with in the devolved nations.

Liberal Democrat leader Sir Ed Davey said: “Boris Johnson gave voters a cast-iron guarantee that he would not raise National Insurance – and now he’s breaking voters’ trust again.

“Even worse, the Government’s plans won’t fix the social care crisis. Our loved ones will still not get the quality care they need.”