Voila. See also Ezra's earlier, very good point about what's good and what's not-so-good about the "public option" not being quite the same frame as "Medicare:"
A Medicare option would also probably have been a nonstarter in Congress, much as the public option attached to Medicare rates stands little chance of passage. But the advantage would have been that the ensuing debate would have been explicitly tied to the thing that makes a government option so effective: the power to negotiate on behalf of a huge customer base, as other countries do and as Medicare does. Instead, the debate has centered around the principle of an insurer run by the public, which is, at this point, going to have a lot less impact on premiums than most of its supporters expect. As a political move, that probably made sense, and allowed politicians to get to a place where they might just have a compromise that supporters like and skeptics don't hate. But the cost is that the compromise won't do what supporters wanted, and skeptics feared.