Andy Burnham, speaking a day after the policy was announced by party leader Ed Miliband, said the plans could also form part of the QOF.
Under the last Labour government a similar 48-hour appointment target formed part of the QOF.
Speaking at the Jubilee Street Practice in east London, which is campaigning against the threat of closure due to MPIG funding withdrawal, Mr Burnham said the new guarantee would be implemented ‘through the QOF wouldn’t it, and through the GP contract. That’s the way that we did it before and it seemed to work’.
Asked to clarify, he said Labour would ‘look at whatever is the most effective way of doing it’.
Mr Miliband said on Monday that Labour would use £100m saved from cutting the NHS competition framework, removing the role of Monitor as an economic regulator enforcing competition, and reducing spending on consultancy, to fund 3 million GP appointments a year.
Labour would reinstate the 48-hour GP access target first put in place under Tony Blair’s government, guaranteeing patients a GP appointment within 48 hours, and the right to book appointments with a named GP further ahead.
The plans would also allow patients to consult a doctor or nurse at their surgery on the same day, and to secure a same-day appointment at the surgery if necessary.
Mr Burnham said the plan was ‘crucial’.
‘Otherwise people, if we are not careful, the public might lose trust in general practice. People are saying this, that we are ringing the surgery in the morning and nothing is available.’
‘The worry is that if people feel that is going to be their experiences they might just say, I'll go to A&E.
‘If you are not careful, you give the public the wrong signals and they walk away from general practice.’
GPs responded sceptically to the plans. The RCGP, which opposed similar proposals mooted by Mr Burnham last year, welcomed Mr Miliband’s announcement, but warned ‘it must not be another ‘sticking plaster’ solution but part of a broader, long-term, shift in investment’.
College chairwoman Dr Maureen Baker asked on Twitter by GP if she thought the funding proposed to support the 48-hour guarantee was sufficient, said: ‘No - but it's a start. Greatest constraint is lack of GP and nursing workforce. But funding will help here.’
Asked by GP if he supported the College's campaign for general practice to receive 11% of NHS funding, Mr Burnham said: ‘I couldn't sign up to that today, but where I will meet the RCGP halfway is in saying it just makes good healthcare sense to give people timely access to GPs.’
GPC chairman Dr Chaand Nagpaul, also took to Twitter to attack Labour's plans. He said the 48-hour ‘target’ would ‘breed perverse behaviour and undermine GPs seeing patients on clinical need. We need capacity not targets.
He added: ‘£100m less than 0.1% NHS budget. Call that investment or valuing general practice? Fails to grasp GP crisis.’
Birmingham LMC secretary and GPC member Dr Bob Morley called funding a ‘gimmicky drop in [the]ocean’.
He said the reintroduction of the ‘failed target’ would ‘have unintended consequences’.
Almost 81% of GPonline readers responding to a poll said they did not back Labour’s plan.