An official with West Midlands Ambulance Service fears they may unable to send ambulances to people because crews are waiting at hospitals for so long to hand over patients.
The number of hours that ambulances are waiting to hand over patients has risen from 5,000 a month to nearly 35,000 a month.
The executive director of West Midlands Ambulance Service, Mark Doherty, says by August the situation could become critical if the delays continue to increase.
He told a meeting of councillors in Shropshire: “By the 17th of August by my reckoning, we'll be losing a third of our ambulance resource.
"So between just pre-Easter and 17th August that situation will be three times as bad as it was. And at that point, the 17th of August, we will fail everything.
"We won't get an ambulance to anybody.”
Today, the local NHS Trusts asked people to only call 999 or go to A&E if the issue is life-threatening.
How long ambulances wait outside hospitals is calculated in what's called "lost hours".
And those hours are increasing month on month. In April last year - they had almost 6,000 (5,732) lost hours.
In January this year, that had risen to almost 26,000 (25,806), and in February it was at 24,971 lost hours.
March was at 33,000 lost hours and up until yesterday, April was almost 35,000 with two more days to calculate.
Trying to cope with the delays is costing the ambulance service an extra £28 million in backfilling delayed crews and hiring extra staff.
They are now asking the local NHS trusts - which commission the ambulance service - for that money. They need 120 extra ambulances too.
Mr Doherty said: “But we said to the commissioners for this year we expect £28 million additional to offset the impact of the handover delays, and even if we get that you know how long it takes to order a car - ordering an ambulance is an 18 month lead-in.”
A West Midlands Ambulance Service spokesman said: "Long hospital handover delays mean some patients are waiting far longer for an ambulance to come to them than we would want.
"We are currently in contract negotiations with commissioners with regards to the provision of services for 2022-23.
"The whole of the NHS remains under severe pressure and we continue to work with local partners to find ways to reduce the handover delays so that our crews can respond more quickly."
A spokesperson for the Black Country and West Birmingham CCG, said: "Our focus is on reducing ambulance handover delays as we recognise the impact on patients, the ambulance service and those working within it, and on the rest of the health and care system.
"We are in the process of negotiating our contract with West Midlands Ambulance Service and are liaising with associate commissioners regarding the proposed contract value.
"Whilst those conversations are ongoing we feel positive about our ability to agree a contract value which ensures WMAS can safely deliver the service locally."
Ahead of this Bank Holiday weekend - usually busier times for ambulances - they've asked people to only dial 999 or go to A&E if the issue is life threatening.
Instead people should use the NHS 111 online service, their local pharmacy or GP.