Only one-in-four GPs surgeries will take part in industrial action planned for Thursday over doctors' pensions, according to reports.
Pulse magazine claimed figures from the NHS trusts showed 281 of 1,265 GP practices have told managers they will take action.
Doctors represented by the British Medical Association will take industrial action on Thursday for the first time in almost 40 years in protest at the Government's controversial pension reforms.
In a separate development, BMA staff are set to go on strike on Wednesday in a row over pay, a day before the doctors they represent.
Routine outpatients appointments, elective operations, and some GP appointments will be postponed as part of the action. However emergency and urgent care will be provided. The BMA has ruled out a complete withdrawal of labour, but if action now goes ahead, doctors will not undertake duties that could safely be postponed.
Health Secretary Andrew Lansley has called on medical staff not to take action, writing in an open letter to BMA chair Dr Hamish Meldrum "the BMA appears set on its path, but I hope that your members will put patients first".
Shadow health secretary Andy Burnham has also called on doctors to halt the strike, saying on Wednesday: "We urge them to step back even at this late stage.
"We understand the level of anger that the doctors have with the government but patients shouldn't be made to suffer."
The UK's largest union, Unite have said the doctors’ strike should be seen in the context that half the NHS workforce currently receiving pensions get £4,000-a-year or less.
Unite’s head of health, Rachael Maskell, said: “The NHS pension scheme has a £2bn surplus, so these changes are unnecessary. What ministers are imposing is nothing short of a tax on NHS employees.
“The government’s proposals have been met with almost universal opposition from the trade unions and professional organisations."
"Every doctor within 10 years of retirement will receive the pension they expected, when they expected. Today's newly qualified doctor who works to 65 will get the same pension as the average consultant retiring today would receive at 60 - the BMA have already accepted a pension age of 65," he said in a statement.
"If doctors choose to work to 68 then they could expect to receive a larger pension of £68,000."
The Patients' Association's Katherine Murphy said patients would lose out: "The only people who will lose out in this are patients. Every extra day that someone waits in pain for an operation or treatment is a day too long.
"It's difficult enough for patients to see their GP as it is and this action will only make the situation worse.
"Patients are also waiting longer for hospital treatment. We would urge the BMA to reconsider."
The BMA's Dr Meldrum said: "Patient safety will be our absolute priority. Doctors will be in their usual places of work and providing urgent and emergency care to all those who need it."
Conservative MP Dr Sarah Wollaston has said a strike would betray patients.
It comes as the Daily Mail reports comments from senior consultant Professor Patrick Pullicino said too many patients were being put on the Liverpool Care Pathway, used for looking after dying patients, which had become an "assisted death pathway rather than a care pathway’."