Obamacare lives.

America's historic health care overhaul, derided by Republicans as intrusive, costly "Obamacare," narrowly survived an election-year battle at the Supreme Court Thursday with the improbable help of conservative Chief Justice John Roberts.

The 5-4 ruling now makes it certain that major health care changes will move ahead, touching virtually every American's life. And Democrats, who have learned to accept if not love the GOP label for the law, heartily praised the decision.

But the ruling also gave Republicans unexpected ammunition to energize supporters for the fall campaign against President Barack Obama, the bill's champion — and for next year's vigorous efforts to repeal the law as a new federal tax

Roberts' vote, along with those of the court's four liberal justices, preserved the largest expansion of the nation's social safety net in more than 45 years, including the hotly debated core requirement that nearly everyone have health insurance or pay a penalty. The aim is to extend coverage to more than 30 million people who now are uninsured