WASHINGTON — In an ambitious road map for slashing the global spread of AIDS, the Obama administration says treating people sooner and more rapid expansion of other proven tools could help even the hardest-hit countries begin turning the tide of the epidemic over the next three to five years.

‘‘An AIDS-free generation is not just a rallying cry — it is a goal that is within our reach,’’ Secretary of State Hillary Rodham Clinton, who ordered the blueprint, said Thursday in the report.