Shadow health secretary Andy Burnham made the call ahead of a House of Commons debate on emergency department admissions on Wednesday.
The coalition government scrapped a target for patients to be seen by a GP within 48 hours in 2010.
Mr Burnham said the move had made it more difficult to get a GP appointment, increasing pressure on A&E.
‘On [David] Cameron’s watch, it has got harder for people to get GP appointments. We hear all the time of people calling the GP surgery early in the morning only to be told that there are no appointments available for days. This is leading to people attending A&E instead or deteriorating while they are waiting and attending as an emergency.’
The government, he said, was denying the problem. ‘This complacency is a danger to patients. Practical steps are urgently needed to help A&Es get safely through the winter.
'That is why, in today’s emergency debate, Labour will call on David Cameron to reverse his scrapping of the 48-hour guarantee this winter and help patients avoid unnecessary trips to A&E.’
But RCGP chairwoman Dr Maureen Baker called the proposals ‘an ill-thought out, knee-jerk response to a long-term problem - which is the profound crisis in the NHS caused by the chronic underfunding of general practice’.
‘Bringing back the 48-hour target for GP appointments will only make a bad situation worse by transferring more pressure onto general practice - at a time when it is in crisis - which could have a profound impact on the safety of patient care.’
She said general practice was facing a crisis just as bad as A&E, caused by resources being redirected to hospitals.
‘In order to stop the rot, the UK's governments need to invest 11% of the NHS budget in general practice by 2017.’