Performance statistics will later be published which will reveal how hospitals have struggled to cope with a surge in patients.
Monthly performance figures for January will reveal how far behind the target of seeing, treating or discharging 95% of patients within four hours the NHS has fallen.
Figures for December were the joint-worst on record, with just 85.1% of patients meeting the four-hour A&E target.
That matched the previous low recorded in January 2017, and there is an expectation the figure for this January will be worse as hospitals have faced the worst flu season in seven years and a general increase in respiratory and other illnesses.
Hospitals were permitted to cancel all elective surgery in January to free up bed space and staff, but operations have resumed this month.
The last two months has also seen large numbers of people facing ambulance handover delays of more than 30 minutes – as many as one in six patients in the first week of the year.
Bed occupancy is running at around 95%, well ahead of the safe guideline of 85%.
Steve McManus, chief executive of Royal Berkshire Hospital in Reading, which sees about 350 patients a day in A&E, told Sky News it had managed to treat 86% of people within four hours in January.
“Our focus is always on trying to achieve those headline national targets because we see those as a measure of quality and experience for patients, and a measure of staff and the way they are caring for patients,” he said.
“We will always be striving for that 95% target because it is an important measure of quality.”
If A&E performance was at a new low in January it will make this the worst winter since current performance targets were introduced 15 years ago, and will raise fresh questions about the sustainability of NHS budgets and structures.
Last week NHS England effectively abandoned the 95% four-hour target for at least a year, using a planning document circulated to hospital trusts to indicate it did not expect the figure to be met across the country until spring 2019.
The Prime Minister has maintained the NHS is better prepared than ever for winter and there has been extensive planning across the system to anticipate demand by increasing the number of beds and diverting patients away from A&E.
Theresa May has also cited an emergency injection of £335m for winter, and an additional £2.6bn for the wider NHS over two years, as evidence that it has responded to demands for more funding.
Should A&E performance have fallen back again despite these measures the Government will face more pressure to meet the long-term demands of the health service.
There is consensus among think tanks and politicians on all sides, including the Conservative chair of the Health Select committee, Sarah Wollaston, that the NHS needs at least £4bn a year more to keep up with demand, a figure backed by NHS England’s chief executive Simon Stevens.