Rachel Reeves has rejected the accusation she is offering voters just “crumbs” of investment in public services.
But the shadow chancellor acknowledged a Labour would not be able to “turn things around straight away” should it win the general election.
In an interview with the BBC’s Sunday with Laura Kuenssberg programme, Reeves was asked what the “big difference” was between Labour and Tory plans for the economy.
Reeves said said there would be an “initial injection of cash” into public services if she becomes chancellor.
She said Labour would spend £1.5bn by removing VAT-free status from private schools and £7.7bn from a “proper” windfall tax on energy companies.
Told that amount of money was “crumbs in the big picture”, Reeves defended her plan.
“Those are not crumbs” Reeves said. “That is real money to go into our public services that the Conservatives are not investing today.”
But Reeves said Labour looked to be inheriting the worst economic situation “since the Second World War” and was “under no illusions” about the challenge.
“I have to be honest that we’re not going to be able to turn things around straight away but we will get to work on all of that,” she said.
Reeves also said she had yet to identify how she would find the £2bn needed to fund pledges to cut NHS waiting lists and fund free breakfast clubs at schools.
Labour had planned to use the money raised by scrapping the non-dom tax loophole.
But chancellor Jeremy Hunt used his Budget to axe the tax status himself and used the money to fund tax cuts.
Having decided not to oppose the tax cuts, Labour now needs to find the £2bn elsewhere.
Reeves said she would not be just “plucking numbers out of the air” and was still “methodically” looking at Treasury documents to work out where to find the money.
Asked if some government departments would face real-terms cuts, under a Labour government, Reeves said she would “quickly” conduct a spending review.