Former Brexit minister Lord Frost has ruled himself out of returning to Downing Street over his opposition to the National Insurance hike.

Some Conservative Brexit-supporters have called for the Tory peer to take on the role of No 10 chief of staff after an expected clear-out over “partygate” allegations.

But Lord Frost said he could not return to help implement the tax hike after Boris Johnson and Chancellor Rishi Sunak committed to imposing it in April despite Conservative anger.

The Prime Minister is widely expected to carry out sackings after senior civil servant Sue Gray’s report into allegations of lockdown-breaching parties in No 10 is published.

Among those whose jobs are thought to be at threat is chief of staff Dan Rosenfield, which would pave a way for Lord Frost’s return after his resignation in December.

However, Lord Frost said on Monday that he would “like to make my thinking clear” given the “mild speculation about my aspirations”.

“The PM’s chief of staff & No10 team must be fully committed to delivering the Government’s agenda. They can’t have agendas of their own or disagree with government policy,” he tweeted.

He reiterated his belief that “policy change is needed if the Government is going to succeed”, adding: “In particular I don’t support the decision this weekend to proceed with tax increases, so obviously I could not return to help implement it.”

Tory backbenchers and opposition MPs have urged the Government to scrap or delay the 1.25 percentage point increase to National Insurance while people face a cost of living crisis.

But the Prime Minister and Mr Sunak doubled down, insisting in an article for the Sunday Times it was “the right plan” to help reform social care and tackle the NHS Covid backlog.

On Monday, Chief Secretary to the Treasury Simon Clarke said it would be a “huge gamble” to instead pay for the measures through borrowing, rather than a tax rise.

“There are very few easy ways to fund more spending on the healthcare system but we have to be honest with the British public that increases to our borrowing would be a very significant risk,” he told BBC Radio 4’s Today programme.

“I don’t think it would be the fiscally responsible thing to do.”

The minister also suggested the Government would not for now be giving in to calls to cut VAT on fuel bills to help struggling families.

“We would rather target our support more closely to need,” he told Today.

“I’m not ruling it out but I’m saying it’s not something at this moment in time we’re leaning towards because we don’t think it’s a well targeted measure.”