Services in the NHS in England are deteriorating in a way not seen since the early 1990s, according to a leading health think tank.
The King's Fund review said waiting times for A&E, cancer care and routine operations had all started getting worse, while deficits were growing.
It said such drops in performance had not been seen for 20 years.
But the think tank acknowledged the NHS had done as well as could be expected, given the financial climate.
Professor John Appleby, chief economist at the King's Fund, which specialises in health care policy, said: "The next government will inherit a health service that has run out of money and is operating at the very edge of its limits.
"There is now a real risk that patient care will deteriorate as service and financial pressures become overwhelming."
He said in terms of how standards were slipping - not how low they had reached - the situation was the worst it had been since the "early 1990s".
The report noted much of the deterioration has happened in the second-half of the Parliament with many measures of performance being maintained in the first few years.
It said the next government had to address the funding situation, adding the extra £8bn a year NHS England says is needed by 2020, was the "minimum" that would be required.
The report - a review of performance this Parliament - highlights a range of problems as well as achievements. These include:
- Waiting time targets for A&E, hospital treatment and cancer care all being missed towards the end of the parliament.
- Bed occupancy increasing to "very high levels", while delays in discharging patients have "risen significantly".
- Funding being increased by 0.8% a year on average - higher than was predicted mainly because of the low levels of inflation.
- Hospital infections, such as MRSA and Clostridium difficile, dropping to historically-low levels.
- Public satisfaction levels reaching their second highest levels ever.
- The number of doctors and nurses increasing, while management costs had been "significantly reduced".
- Levels of deficits increasing though as the NHS struggles to keep up with demand.
The report is the second part of the King's Fund pre-election review of the NHS this Parliament.
Last month it warned the coalition government's reforms of the health service had been "damaging and distracting".
The King's Fund report should make worrying reading. The reference to the 1990s conjures up images of - for the NHS at least - a bygone era.
The think tank's point was not that waiting times had reached the level they were at then, rather that this is the first time in two decades of almost continuous improvement that there has been a sustained drop in performance.
In many ways, that had to happen. Services cannot keep getting better for ever.
Nonetheless, the findings are crystal clear: the NHS is at a critical juncture.
But what is less easy to determine is to what extent the coalition's policies have contributed to the difficulties.
The think tank has already provided a critical analysis of the government's reforms - and when pushed, acknowledged the health service may have been "in better shape" if they had not happened.
But the more significant issue for the health of the health service this Parliament has been the squeeze on finances. Even though the budget has been increased, it has felt more like a cut to many because demands have risen so quickly.
On this though, the King's Fund accepted that the government's hands were tied. Given the state of the economy, ministers did about as much as they could have.
Royal College of Nursing general secretary Peter Carter said politicians needed to take note of the warnings made by the King's Fund.
"Morale is low, and more and more staff are being made sick with stress because of the intolerable pressure they are under," he added.
Katherine Murphy, of the Patients Association, said: "The findings echo what we are hearing on a daily basis on our helpline. It is clear to the public that the future of the NHS is one of the most important issues facing the nation and it should be a central issue in the election campaign."
Shadow Health Secretary Andy Burnham said: "Five years ago David Cameron stood on a promise to protect the NHS. This report provides authoritative proof that he has broken that promise."
But a Department of Health spokesman said: "As the King's Fund says, the NHS has 'performed well in the face of huge challenges', but if we are to continue to invest in the NHS going forward it needs to be backed by a strong economy."