Krugman writes in his NYT blog:

Rudy Giuliani warned us about what would happen if a Democrat wins:

You have got to see the trap. Otherwise we are in for a disaster. We are in for Canadian health care, French health care, British health care.

And that would be a terrible thing

Short version: The US health care system is already a disaster being made worse under a Republican President. "By 2002–03, the U.S. fell to last place" in deaths that "are potentially preventable with timely and effective health care" in a study of 19 industrialized nations. Of course all of the countries that bested the US have some form of universal health care.

Bottom line: Rudy wants voters to grant him and his wife "CheneyCare" by saying it would be a disaster if you and your family had it too.