In his speech, Sir Keir defended the Budget as making “necessary” and “fair choices”.
He acknowledged that “tax rises do make life harder for people” but argued the alternatives were cutting public services, ignoring child poverty or extra borrowing.
The PM said the Budget “was a moment of personal pride”, highlighting how the decision to scrap the two-child benefit cap would lift hundreds of thousands of children out of poverty.
He also promised to push ahead with reforming the welfare system, which he said had “trapped people in poverty” and “wrote young people off as too ill to work”.
Over the summer, the government abandoned planned benefit cuts in the face of a major rebellion by Labour MPs.
Challenged over whether he could get the support of his own MPs to reform the system, Sir Keir said this was a “moral mission” and there was a “strong consensus” on the need to get young people into work.
He did not give further details about potential reforms, saying two ongoing reviews into “Neets” – 16-24-year-olds who are not in education, employment or training – and another on health and disability benefits needed to “complete their course”.
The prime minister also insisted the Budget would boost economic growth, despite the OBR concluding that not a single measure it included would change the watchdog’s growth forecast for the next five years.
Sir Keir said he was “confident we can beat the forecasts”, after the OBR predicted the economy would grow at a slower rate than previously expected from next year.
He vowed to cut “unnecessary red-tape” and regulations to get the country building.
Meanwhile, he said the Brexit deal had “significantly hurt our economy” and promised to “keep moving towards a closer relationship with the EU”.
However, Lib Dem leader Sir Ed Davey said: “Keir Starmer’s speech talked about boosting growth but he is refusing to do the single biggest thing to achieve that – fixing our trade with the EU through a new customs union.”
