Borrowing more money to invest into the UK is “the right economic thing to do”, the chancellor has said.
The Bank of England announced a cut in interest rates on Wednesday.
But the Resolution Foundation warned of a £575 a year blow to households, even before the impact of coronavirus.
Labour’s John McDonnell told the BBC’s Today programme he welcomed more investment from the government, but “10 years of austerity brought the country to our knees” and the Budget was “only going part way to making up” for Tory cuts.
As well as a £5bn emergency response fund for the NHS and a number of other measures to tackle the coronavirus outbreak, he announced spending of over £600bn on roads, rail, housing and broadband across the next five years.
“We can look at that as see we are on the right track with the plans we are doing, and it will start to have an immediate effect on people,” he told Today.
Former Prime Minister Theresa May urged “restraint and caution” on spending after the Budget announcement.
She told the Commons: “Although spending a lot of money may be popular and may seem the natural thing to do, there is, of course, that necessity to have a realistic assessment of the longer term impact of those decisions and of the longer term consequences.
“It is also necessary to ensure that we have that restraint and caution that enables us to make the public finances continue to be strong into the future.”
Mr Sunak defended his plans, saying he would be sticking to the fiscal rules set out in his the Tory’s election manifesto.
“That is, I think, the right economic thing to do, whilst overall having stable management of our debt.”