Junior doctors have voted to reject their new contract, despite their union agreeing to it in a bid to end an unprecedented series of strikes.
The British Medical Association (BMA) negotiated the fresh contracts, having resumed talks after strikes earlier this year, the first of their kind in decades.
But its junior doctor members voted to reject it, by 58% and 42%, prompting the BMA's Johann Malawana to resign as chairman of its junior doctors' committee.
The result is a setback for the BMA, which supported the new deal that was put to its members, having stoked anger among its members over the government's imposition of an earlier version of the contract.
The result is also a big blow to Health Secretary Jeremy Hunt, as the BMA's support for the new contract allowed him to claim he had resolved the deadlock.
Hunt told the BBC he "owed it to the country to make a rapid decision", when asked if he would now impose the contract on junior doctors.
In his resignation letter, Malawana said the industrial action had "forced a government back to the negotiation table twice".
He added: "I hoped the resulting contract would be acceptable to our amazing membership.
"However, I believe the fundamental breakdown in trust caused by the government's actions over the last five years has resulted in a situation where no solution is possible particularly when a government is so keen to declare victory over frontline staff."
Some 68% of those eligible turned out to vote on the deal - some 37,000 junior doctors and medical students
Malawana also said: "Having spoken to many junior doctors across the country in recent weeks it was clear that, while some felt the new contract represented an improved offer, others had reservations about what it would mean for their working lives, their patients and the future delivery of care in the NHS.
"There was also considerable anger and mistrust towards the Government’s handling of this dispute.
"These concerns need to be fully addressed before any new contract can come into effect.
"There is much to do to in order to rebuild the trust that has been eroded over the last year. The Government must now do the right thing, accept the outcome of this vote and work constructively with the BMA to address junior doctors’ concerns with the new contract."