Mitt Romney’s web site makes a bold promise: “On his first day in office, Mitt Romney will issue an executive order that paves the way for the federal government to issue Obamacare waivers to all 50 states. He will then work with Congress to repeal the full legislation as quickly as possible.”

The election of Elizabeth Warren to the Senate might serve as a firewall against attempts to repeal Obamacare.

Many of Romney’s supporters assume that this is what will happen if he wins. But in truth, even if Republicans take both the White House and the Senate, Romney wouldn’t have the power to “repeal the full legislation.” Nor could a new president grant waivers that would let states ignore the Affordable Care Act (ACA). We live in a nation ruled by law, not magic wands.