Senate Democrats passed historic healthcare legislation Thursday that could define President Barack Obama's legacy and brings major changes to the medical-insurance industry and new health coverage for tens of millions of uninsured Americans. On a party-line 60-to-39 vote, Democrats supported the most significant shifts in health policy in four decades. The early-morning vote followed months of political debate that consumed the U.S. Congress and hurt Obama's approval ratings. Thursday's vote clears the way for difficult negotiations in January with the House of Representatives, which approved its own healthcare overhaul in November that features different approaches on taxes and a proposed new government-operated insurance program. Both bills would extend health insurance to more than 30 million more Americans. Democrats hope to complete work on reconciling the two versions before Obama's State of the Union speech in late January.