BJP leader Narendra Modi.

Indian Prime Minister Narendra Modi has asked for a drastic cutback of an ambitious health care plan after cost estimates came in at $18.5 billion over five years, several government sources said, delaying a promise made in his election manifesto.

Modi has had to make difficult choices to boost economic growth - his government's first full annual budget, announced last month, ramped up infrastructure spending, leaving less federal funding immediately available for social sectors.