In the three years since President Obama signed the Affordable Care Act into law, it has survived more than 50 votes in Congress to defund or repeal it, a Supreme Court challenge, a presidential election and, as of Tuesday morning, a government shutdown. Much of the spending for the law is mandatory and won't be cut off.
But now, it must survive its own implementation.
Tuesday is the day that Obamacare goes operational. Americans can begin signing up for health insurance on online marketplaces known as exchanges.