Health Secretary Sajid Javid cannot say if the NHS backlog will be cleared within three years despite billions of pounds of fresh spending.
Chancellor Rishi Sunak will use his Budget on Wednesday to commit a further £5.9 billion in capital funding to help sort the crisis created by the coronavirus pandemic.
That cash comes on top of £12 billion announced last month, but Mr Javid said it is “impossible to know” how well the issue will be tackled in the coming years.
The Health Secretary said the NHS waiting list is 5.7 million people at the moment, but estimated it could grow as high as at least 7 million.
Asked whether it will be solved within three years, he told BBC Radio 4’s Today programme: “I’ve been very open about this, it’s going to go up before it comes down.”
Pressed on how much of the backlog will be sorted in that time, Mr Javid said: “I’m not going to put a number on it – it’s impossible to know because I don’t know how many people will eventually come back to the NHS.”
He said the latest funding will be spent on capital investment on physical items such as beds, IT equipment and scanners.
Mr Javid insisted that along with spending from the National Insurance hike it will “drive down that waiting list and make sure more people get seen as quickly as possible”.
But with figures from the NHS Confederation, which represents health bodies, showing the NHS is short of 80,000 staff, Mr Javid faces calls for further funding.
Dr Layla McCay, director of policy at the confederation, said the new spending will “go a long way” but further investment is required.
“While it will be really helpful, particularly in addressing the backlog, we need to remember that the NHS does need a little bit more than that in order to properly restore services and work through the additional expenses that have been created by Covid-19,” she told Times Radio.
“So certainly that money will go a long way, but I think that we will also need to see investment in other areas.”
Mr Sunak’s previous budgets in March 2021 and 2020 were heavily focused on supporting the country through the coronavirus pandemic.
He now wants to rebuild the nation by focusing on skills, innovation and economic growth while trying to sort public finances amid soaring debt levels.
The capital funding for the NHS is hoped to deliver around 30% more elective activity by 2024/25 compared with pre-pandemic levels.
Around £2.3 billion will be used for checks, tests and scans by creating 66 more diagnostic centres across England.
But the Chancellor faces a number of major challenges, not least a warning from the Bank of England’s new chief economist that inflation could rise above 5%.
More than £30 billion of spending has already been committed across numerous announcements from the Treasury over the weekend, the largest being £7 billion for transport infrastructure outside London.
Despite the swathe of pre-Budget announcements, Mr Sunak would not be drawn on whether he could rule out tax rises before the next election.