The popularity of Rishi Sunak has plummeted among Tory members after he oversaw a manifesto-breaking tax rise.

       The Chancellor had the second-highest approval rating in the Cabinet in a poll of party members in August – but has dropped to 12th in a new poll this month.

       Mr Sunak played a central role in the announcement that National Insurance contributions would rise by 1.25 percentage points to cover higher NHS spending and social care reform.

       The move in September, which broke a pledge in the 2019 election manifesto, triggered frustration among party backbenchers and grassroots members.

       Regular polling, which asks Tory members whether they are satisfied with the performance of each Cabinet minister, is conducted by the Conservative Home website.

       In August, Mr Sunak had a rating of plus 75.4 percentage points, meaning the number of members who approved of his performance far outweighed those who disapproved.

       But the October numbers showed that rating had fallen to plus 45.4, with 11 Cabinet ministers given higher approval ratings.

       The 11 ministers Mr Sunak was behind were, in order of rating, Liz Truss, Lord Frost, Ben Wallace, Anne-Marie Trevelyan, Nadine Dorries, Nadhim Zahawi, Sajid Javid, Stephen Barclay, Jacob Rees-Mogg, Therese Coffey and Michael Gove.

       The tax burden is set to rise to its highest level in 70 years after this year's two Budgets, but Mr Sunak's Budget speech last week included a section in which he said it was his "mission" to cut taxes before the next election, due in May 2024.

       Alok Sharma, the president of the Cop26 UN climate change summit, was the Cabinet minister with the lowest approval rating in the October poll. He has become one of the public faces of Mr Johnson's push to get the UK to net zero carbon emissions by 2050.