Speaking at the House of Commons last week, he said that introducing new providers was essential if the government's drive for improvement was to become self-sustaining.
Mr Blair said: 'That means ensuring that on the supply side there's scope for diversity and, on the demand side - the patient - there's the ability to go elsewhere if the local service is not up to scratch or is not convenient or accessible. That's the reason for the changes we are making at the moment.'
Where GP services were full, the government would ensure patients could access different services from the private or voluntary sector.
'This is critical to re-engineering the system,' he added.
Mr Blair insisted that he would not tolerate the status quo on GP provision: 'What can't happen is a situation where you don't have a proper number of GPs in an area to service people and simply say we are not allowing anyone else to come in.'
But he said that, for now, the government was content to limit support for alternative providers to the most disadvantaged areas.
However, this could mean half of all PCT areas. According to the primary care White Paper, the DoH is to offer help to under-served areas: which it defines as those with fewer than 57.88 GPs per thousand of the population of England. Currently 144 PCTs out of 300 fall into this category.