Hard-pressed Brits face a National Insurance hike on April 6 after Boris Johnson ruled out claims he is preparing a U-turn.
Downing Street said the tax rise from 12% to 13.25% will happen “no ifs, no buts” after claims the PM was “wobbling” over it to save his job.
The PM’s deputy spokesman said the Prime Minister and Chancellor were “fully committed” to the £12bn-a-year hike and “we’re introducing it in April”.
But a Tory grandee cast doubt on Downing Street’s claims, telling the Mirror: “I’m sure they will say all that. Nothing has been put to bed”.
They added: “The purpose at the moment should be getting the economy moving… It’s certainly in play at the moment for Conservative MPs.”
And defence minister James Heappey admitted on BBC Question Time: "Everybody in the room is against it. Everybody in the room is feeling the squeeze."
Staff will pay 13.25% on what they earn above £797-a-month from April 6 - up from 12% now - in a bid to raise £12bn a year for NHS and social care.
The Resolution Foundation says households on median income will lose roughly £300 a year due to the rise.
For the poorest half of households it is £140 a year, while for the wealthiest half it is £730.
It will come at the same time as rises in energy bills, rail fares and prices of everyday items in the shops.
Some Tory MPs were planning to press for a U-turn while Mr Johnson faces the threat of a no confidence vote over Partygate.
Earlier this week, Downing Street and Boris Johnson repeatedly refused to guarantee the rise would go ahead as planned in April.
One source said: “Whether he actually does it or not will depend on whether he thinks he needs to do it to win the vote."
But today the No10 spokesman said: "The Prime Minister and Chancellor are fully committed to introducing the health and social care levy in April.
"We are doing that in order to give the NHS the funds it needs to tackle the backlog that has built up, as well as tackling the long-term issue of social care."
U-turning on the rise would have sparked a ferocious row with Chancellor Rishi Sunak.
Labour leader Sir Keir Starmer said the National Insurance rise was “the wrong thing to do”, adding: “The Prime Minister needs to act on this.
“We’ve got a very serious issue here with everybody facing prices going up – whether that’s fuel, energy bills at home, inflation going up to something like 6%, the worst it’s been since the John Major years."
Senior Tory Rob Halfon told BBC Radio 4’s Today programme: “We are going to have a cost-of-living crisis next year. It is not just going to suddenly magic away.
“People are struggling at the moment because of everything that has happened… What I think the Government should do is look at it again.”
Mel Stride, the Tory chair of the Commons Treasury Committee, called for the rise to be delayed by a year as there is more “wiggle room” to hit economic targets and a cost-of-living crisis.
Shadow chancellor Rachel Reeves added: “I think you have to explain where every pound is going to come from, and that is why I think it is right to ask those who can pay a bit more and to ask those with the broadest shoulders to make the contribution.
“This is the wrong tax at the wrong time. It is a tax on ordinary working people and on jobs.”
Defence Minister James Heappey said ministers had agreed the National Insurance rise but “the top of the government is in listening mode at the moment”.
He told BBC Question Time: “I know and it’s the same for all of us that prices are rising quickly. There is a challenge to how we make ends meet.
“Certainly I think we’re going to need to do a lot over the next few years to help people with this.”
No10 refused today to say if the Prime Minister and Chancellor were meeting to draw up help for people’s energy bills. A plan was reportedly delayed due to chaos over the Sue Gray report on parties.
