Ministers have rejected calls for a rethink on National Insurance (NI) increases for millions of self-employed workers announced in the Budget.
The measure, which breaks a 2015 manifesto pledge on NI contributions, would result in 1.6 million people paying £240 on average more every year.
Treasury Chief Secretary David Gauke ruled out a U-turn, saying the move would make National Insurance fairer.
Critical Tories said it did little to encourage enterprise and risk-taking.
Laura Kuenssberg said the extent of the political fallout was not clear yet but Downing Street would be “disappointed” by some of Thursday’s newspaper reaction, with The Sun’s front page headlined “Spite van man”.
“I think people understand the fairness point.
“At a time when – unlike what has happened in the past – essentially the benefits that the self-employed receive for their contributions are largely the same as employed people do, it is wrong that employed people pay a lot more in National Insurance contributions.”
The Conservatives’ last general election manifesto explicitly ruled out rises in National Insurance, VAT and income tax during the lifetime of the current Parliament.
During the campaign, the then-Prime Minister David Cameron continually repeated the commitment in public and contrasted it with the “jobs tax” which he said people could expect if they elected a Labour government.