The U.S. Supreme Court upheld the core of President Barack Obamas health-care overhaul, giving him an election-year triumph and preserving most of a law that would expand insurance to millions of people and transform an industry that makes up 18 percent of the nations economy. The justices, voting 5-4, said Congress has the power to make Americans carry insurance or pay a penalty. That requirement is at the core of the law, which also forces insurers to cover people with pre-existing health conditions. The court limited the laws extension of the Medicaid program for the poor by saying the federal government cant threaten to withhold money from states that dont fully comply.