Thousands of ambulance workers are to be balloted on whether they want to take industrial action over pay.
It comes as unions accused the Government of failing to honour promises, made a year ago, to improve ambulance staff's pay and conditions in England.
The "consultative ballot" was announced today as the NHS prepared for a two-day walk out of junior doctors.
Lives are being put at risk because ambulances are taking up to three minutes longer on average to reach the most seriously ill patients, according to Labour.
Chaos at accident and emergency departments means ambulances are trapped in queues outside, which has a knock-on effect on the time it takes to deal with 999 calls, the party said.
Records published by the Health and Social Care Information Centre show life-threatening call outs are taking an average of 67 seconds longer than in 2011.
That rises to two minutes and 21 seconds in the East Midlands, taking its response time just over the target eight minutes.
Shadow health secretary Andy Burnham said: "These figures raise real concerns that lives are being put at risk by the chaos in the NHS."
Health Secretary Jeremy Hunt has said that too many elderly people were ending up in hospital because of the flawed GP contracts introduced by the Labour government.
Mr Hunt told the Daily Telegraph: “Labour’s disastrous 2004 GP contract left many vulnerable elderly patients without good out-of-hours care, so it’s rank hypocrisy for them now to complain about the consequences of their historic mistake.
"We have ripped up that contract and are bringing back proper family doctoring, with named GPs for older people to help relieve A&E pressures.”
He added that they allowed family doctors to abandon responsibility for out-of-hours care.
Age UK has said that some of those admitted to hospital is a consequence of "not getting good quality care at home".
Caroline Abrahams, charity director at Age UK, said: "It is important that older people receive the treatment and care they need and sometimes this means going to hospital.
"However we know that in some cases being admitted to hospital is the consequence of not getting good quality care at home."
Access to high quality social care is increasingly difficult as many vital services are withdrawn or reduced as a result of the current crisis in care.
"The core of the problem is that funding for social care has failed and is still failing to keep up with growing demand. Legislative reform is vital but pointless unless sufficient funding is in place."
Labour said the ambulance figures confirm that cuts to social care funding are driving up the need for hospital attention among the elderly.
Shadow health secretary Andy Burnham said data in the House of Commons library shows that local authority spending on adult social care has been cut by £1.8bn since 2009/10.
He said: "These shocking figures expose the growing crisis in older people's care on David Cameron's watch.
"The Government's severe cuts to social care have left thousands of older people without the support they need - at risk of going into hospital and getting trapped there. It is one of the root causes of David Cameron's A&E crisis.
"It is appalling to think that every week there are thousands of frail and frightened people speeding through our towns and cities in the backs of ambulances to be left in a busy A&E."
The number of very elderly people needing to go to hospital by ambulance has risen 81% since 2009/10, according to new figures.
Analysis by Labour showed that 300,370 people over the age of 90 were taken to A&E by ambulance in the last year, a substantial rise on previous years. In 2009/10 the figure was 165,910.
The data comes from tables of ambulance activity in England published by the Health and Social Care Information Centre (HSCIC).
Ambulance drivers will go on strike today in a bitter row over cuts and union recognition.
Staff and paramedics will mount picket lines outside ambulance stations across the county.
Unite said its 450 members at the Yorkshire Ambulance Service NHS Trust will walk out for 24 hours after the failure to break the deadlock.
Members of other unions are not involved in the action and will be working normally to provide emergency cover and other services.
Unite said it was de-recognised after raising concerns about patient safety over plans to make savings of £46 million over the next five years.
The union said there were proposals to employ emergency care assistants, with only a few weeks training, alongside paramedics.