Ed Miliband has told voters there are "less than 48 hours to get rid of this Tory government and David Cameron" as he placed the NHS at the centre of his campaign again.
Mr Miliband told an audience in Bedford that the health service was facing a "financial timebomb" with the Tories planning "savage cuts".
He said he wanted to put the "right values" including "care, compassion and corporation" back at the centre of the NHS.
The Labour leader said he would keep going "right till the last minutes" to rescue the National Health Service and prevent another five years of Conservative government.
ITV News' Carl Dinnen, who is following Labour's campaign, said Mr Miliband had admitted "this race could be one of the closest in our history" as he outlined the choice facing voters on Thursday.
Andy Burnham has warned that the Conservatives "extreme spending plans" would put the NHS at risk if they were re-elected.
The shadow health secretary accused the prime minister of setting policies that had increased the deficit in the NHS and pledged that Labour's mansion tax would put funds back into the health service.
"The financial crisis in the NHS is biting this year, with patients seeing treatments rationed, services closed and hospitals without enough staff," Burnham said.
"Hospitals were forced to spend £1 billion on agency staff last year because of the shortage of nurses under David Cameron.
"Only Labour's plan to recruit an extra 20,000 nurses - paid for with £2.5 billion extra a year - will allow hospitals to break the hold of the staffing agencies and get their finances into better shape."
Ed Miliband is warning of a "financial bombshell" that means most English hospitals face having to cut staff, beds and services this year.
As the election campaign enters its final 48 hours, the Labour leader said a "cash crisis made in Downing Street" is putting severe strain on the NHS and will mean major budget cuts in the coming months.
Labour analysis of leaked documents produced by NHS Providers, which represents trusts across the hospital, ambulance and mental health sector, show financial forecasts for 98 trusts projects their combined deficit this year will reach £759 million - up from £250 million for the last financial year.
The party claims that equates to £1.86 billion across England's 240 trusts.
Right now, our NHS is in grave danger because David Cameron has broken his promises on the NHS.
Two-thirds of hospitals face having to make swingeing cuts, not some point in the future, but this year because of a cash crisis made in Downing Street. That will mean staff cut, beds lost and services closed.
Ed Miliband is demanding the Conservatives must "come clean" over their plans for the NHS amid claims of greater privatisationRead the full story ›
Labour have blasted Jeremy Hunt after he admitted voters did not believe the Tories over the NHS.
Shadow Health Minister Andy Burnham said: "Jeremy Hunt has finally conceded what everyone knows to be true, you can't trust a word the Tories say on the NHS.
"The reason why they have a credibility problem is because they have a track record of failing to keep NHS promises.
"Last time out, they promised 'no top-down reorganisation' - but then brought forward the biggest in the history of the NHS.
"People won't believe David Cameron on the NHS at this election because they know he hasn't got a clue where the money is coming from. They know you can't fund the NHS on an IOU.
"While Labour has a better, fully funded plan to invest in the NHS, the Tories have a plan for extreme cuts which will see them cut the NHS."
Jeremy Hunt has compared modern politics to dating app Tinder and called for a return to old-fashioned doorstep canvassing.Read the full story ›
Ed Miliband has told supporters that the IFS assessment of party manifestos showed the Tories were committed to "extreme spending plans".
"They have also confirmed that Britain would be facing the deepest cuts over the next three years of any advance country in the world," the Labour leader said during a visit to Nuneaton in Warwickshire.
Miliband continued: "It is a plan so extreme that far from protecting the NHS they would end up cutting the NHS.
"It is a plan so extreme that it wouldn't mean three years of the good life, it would mean three more years of the hardest of times."
Ed Miliband has unveiled a new poster campaign with Labour's proposals for a "better plan for the NHS".
ITV News Political Correspondent Carl Dinnen reports from Nuneaton:
Labour has accused the Tories of planning the biggest spending cuts in any of the world's advanced economies since the Second World War.
Ed Miliband warned the Conservatives plan to balance the books would result in 20,000 fewer police officers and the closure of 1,000 sure start centres.
He will tell a rally in Leeds: "It is a plan so extreme that International Monetary Fund figures show Britain would be facing the deepest cuts over the next three years of any advanced country in the world.
"It is a plan so extreme that far from protecting the NHS they would end up cutting the NHS. It is a plan so extreme that it wouldn't mean three years of the good life, it would mean three years of hard times.
"Maybe not for some of the rich and powerful, who have done so well with the last five years of the Tories. But it would mean hard times for the working families of Britain, who put in the hours, pay their taxes and play their part."