Philip Hammond has come under increased pressure from within his own party as a number of Tories call for him to review his National Insurance hike for the self-employed.
In a series of interviews after his announcement, Mr. Hammond defended the policy, saying his plans in the Budget were “fair and appropriate.”
However, at least 10 Conservative backbenchers have voiced their concerns about the increase, which has added fuel to Labour’s hopes of forcing a government U-Turn over the issue.
The Chancellor has now said he is "prepared to listen to backbenchers" on the controversial measure, and Downing Street has declined to rule out a review of the decision.
Now, Iain Duncan Smith – the former work and pensions secretary – has lent his voice to the MPs calling Mr. Hammond to review the policy.
He told Sky News: "I would like to see this kept under review. I would like to see the ball kept in play.
"This [the NI increase] doesn't land until next year, so there is plenty of scope to look at how this actually affects [self-employed people] and to listen to business representatives."