The incendiary claim came after Mr Johnson made one of his biggest gambles in office, introducing a new National Insurance levy to fund social care. From April next year National Insurance will rise 1.25 percent, to fund NHS spending and a £86,000 cap on individual social care payments.
Speaking to The Times a cabinet minister claimed Mr Johnson wants to be Prime Minister for “longer than Thatcher”, who held the post between 1979 and 1990.
They said: “Boris will want to go on and on.
“The stuff Dom [Cummings] was saying about him going off into the sunset was nonsense.
“He’s very competitive. He wants to go on for longer than Thatcher.”
In June Dominic Cummings, formerly Mr Johnson’s chief advisor, said the Prime Minister had a “clear plan” to quit two years after the next general election, expected in 2023 or 2024.
He argued Mr Johnson wants to be “making money” and having fun, rather than trying to stay at 10 Downing Street for the long-term.
This timeframe would see the Prime Minister step down in 2025 or 2026, if he wins the next general election.
Earlier this year Mr Johnson was interviewed by journalist Sebastian Payne for ‘Broken Heartlands’, a book about how Labour lost much of the ‘red wall’ in 2019.
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“The Treasury has made a catastrophic mistake in the last 40 years in thinking that you can just hope that the whole of the UK is somehow going to benefit from London and the southeast.
“There is potential for everyone, but there isn’t the same opportunity.”
Mr Cummings has turned on Mr Johnson sharply since leaving Downing Street late last year.
In May, appearing before a Commons select committee, he branded the Prime Minister “unfit for the job”.
Mr Johnson was compared to “a shopping trolley smashing from one side of the aisle to the other”.
On Wednesday the House of Commons approved the Government’s National Insurance hike, by 319 voted to 248.
Despite speculation of a Tory rebellion, only five Conservative MPs voted against the plans.
Labour leader Sir Keir Starmer argued the proposals won’t fix the social care crisis.
He said: “The truth is his plans don’t do what he claims.
“People will still face huge bills, many homeowners will have to sell their homes.”