Nearly five years after President Barack Obama signed his health care overhaul into law, its fate is yet again in the hands of the Supreme Court.

This time it's not just the White House and Democrats who have reason to be anxious. Republican lawmakers and governors won't escape the political fallout if the court invalidates insurance subsidies worth billions of dollars to people in more than 30 states.

Obama's law offers subsidized private insurance to people who don't have access to it on the job. Without financial assistance with their premiums, millions of those consumers would drop coverage.

And disruptions in the affected states don't end there. If droves of healthy people bail out of HealthCare.gov, residents buying individual policies outside the government market would face a jump in premiums. That's because self-pay customers are in the same insurance pool as the subsidized ones.

Health insurers spent millions to defeat the law as it was being debated. But the industry told the court last month that the subsidies are a key to making the insurance overhaul work. Withdrawing them would "make the situation worse than it was before" Congress passed the Affordable Care Act.

The debate over "Obamacare" was messy enough when just politics and ideology were involved. It gets really dicey with the well-being of millions of people in the balance. "It is not simply a function of law or ideology; there are practical impacts on high numbers of people," said Republican Mike Leavitt, a former federal health secretary.

The legal issues involve the leeway accorded to federal agencies in applying complex legislation. Opponents argue that the precise wording of the law only allows subsidies in states that have set up their own insurance markets, or exchanges. That would leave out most beneficiaries, who live in states where the federal government runs the exchanges. The administration and Democratic lawmakers who wrote the law say Congress' clear intent was to provide subsidies to people in every state.