The King's Fund has called for more money to be found in the autumn statement to prevent a financial crisis in the NHS.
The NHS financial settlement for 2015/16 has already been agreed, with an increase of 0.2% to the NHS budget.
However The King's Fund has argued more money is needed to maintain staffing levels, quality of care and keep waiting times from rising.
The King's Fund's briefing has highlighted recent figures showing that provider trusts in the NHS are in deficit by £630m.
The briefing also notes that NHS performance is already slipping and overall A&E waiting times are at their highest for a decade and overall waiting time targets being breached on a regular basis, recent figures have shown.
The King's Fund has called for a new transformation fund to be established early in the next parliament to pay for community-based services and help transitions to new models of care.
Chris Ham, chief executive of The King's Fund said: "There is scope to improve productivity in the NHS, but this will not be enough to respond to unprecedented pressures on budgets and meet rising demand for services.
"Recent pledges from the main political parties to increase funding are welcome but it is clear that none of them have yet addressed the scale or the urgency of the financial challenge facing the NHS.
"With deficit reduction still a high priority, finding an additional £2 billion in the Autumn Statement is a very big ask. However, unless more money is found, a financial crisis is inevitable next year and patients will bear the cost as waiting times rise and quality of care deteriorates."
