Shadow chancellor Rachel Reeves said that Labour would not go ahead with the rise - made up of 1.25 per cent each on employers’ and employees’ payments.
And she said that Mr Sunak still has time to halt the controversial rise before it comes into effect in April.
Conservative MPs are piling increasing pressure on the chancellor to rethink the tax rise, intended to fund improvements to the social care system as well as helping the NHS deal with the backlog of cases which has built up during the Covid pandemic.
Leader of the Commons Jacob Rees-Mogg broke ranks at last week’s cabinet to call for the rise to be halted.
Ms Reeves said it appeared Mr Sunak would have to be “dragged kicking and screaming” into dropping the £12bn hike, which will raise the overall tax take to its highest sustained level since the 1950s at a time of a cost-of-living crisis.
Challenged over whether Labour would reverse the rise, Ms Reeves told BBC1’s Sunday Morning: “If we were in government, we would not be going ahead with it now.
“They still have time to act. The government can do the right thing.
“There is another fiscal statement from the chancellor set for 23 March, just over a week before this tax increase is due to come in.
“I want the government, I want the chancellor to rethink. The chancellor has to be dragged kicking and screaming to every announcement he makes.
“You’ve now got a chorus of Conservative MPs as well as the Labour Party saying ‘Do the right thing, think again on National Insurance’.
“This double whammy of a National Insurance hike at the same time that gas and electricity bills are going to be going through the rood is just a catastrophe that families and pensioners cannot afford.”
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