Institutional responsibility
What the PMO is
The PMO's suo motu disclosure says: “Under the Allocation of Business Rules 1961, the Prime Minister's Office (PMO) provides secretarial assistance to the Prime Minister.” It adds that the “PMO is headed by the Principal Secretary to PM”, and describes its decision-support function as “assisting, as required, for decisions on proposals received”.
PMO suo motu disclosure · pmindia.gov.in (PDF)