The NHS in England has missed its target for A&E waiting times every month for two years, new figures show.
Some 90.3% of patients were admitted, transferred or discharged from A&E in four hours or less in July, missing NHS England's 95% target, which was last achieved in July 2015.
The figures also show that in June 2017 there were 3.83 million people on waiting lists, the highest figure since December 2007.
The NHS Confederation, which represents health organisations in England and NHS Employers, said the current system was "unsustainable".
Its deputy chief executive Danny Mortimer said: "Performance against these targets shows the system is under pressure and needs transformation and investment.
"(Politicians) should be more willing to fund health and social care, more supportive of radical change, more prepared to back services not buildings and more courageous in supporting new models of care that bring about better outcomes for patients."
Labour leader Jeremy Corbyn said NHS patients could not "afford another year of Theresa May".
"The crisis in social care is crippling our hospitals as more people have delayed discharges because there isn't proper care available for them outside," he said.
"Labour would immediately put £2 billion into social care."
Figures released on Thursday also show there were 500,498 emergency admissions in July 2017 - only the third time since records began that emergency admissions in a month have topped half a million. It is also the first time July emergency admissions have done so.
An NHS England spokesman said nine out of 10 patients were being admitted, treated, and transferred or discharged from A&E within four hours, which was "up on the May 2017 performance".
He said: "Reducing delays for patients awaiting discharge from hospital remains a key priority ahead of winter, and it is positive that NHS-related delays are lower this year than last."
The number of people waiting more than 18 weeks for consultant-led treatment, which the NHS says should be the maximum time it takes to start treating them, has also steadily increased.
In the first six months of 2017, an average of 369,007 patients waited longer than 18 weeks to start treatment after being referred by their GP.
The average figure for the same period in 2016 was 289,195, while in 2015 it was 208,489.
The NHS estimates the total number of patients on waiting lists for treatment at the end of June 2017 may have been slightly more than four million, as five trusts did not submit the relevant figures.
If their estimate is correct, it would be the first time the number of people on waiting lists, including estimates for missing data, has exceeded four million since records began in August 2007.