President Obama is proposing to begin a vast expansion of the U.S. health-care system by creating a $634 billion reserve fund over the next decade, launching an overhaul that most experts project will ultimately cost at least $1 trillion. The "reserve fund" in the budget proposal being released today is Obama's attempt to demonstrate how the country could extend health insurance to millions more Americans and at the same time begin to control escalating medical bills that threaten the solvency of families, businesses and the government.