Why conservatives hate and fear universal health care

Bill Kristol made the argument to Republicans in the early 90's the last time the Democrats held power, and the Cato Institute makes it again now that the Democrats are in power again:

Universal health care is lethal to conservatism.

A "single payer" national health system - known as "socialized medicine" in the rest of the developed world - should be an essential part of the change that the core constituencies which elected Obama desperately need. Britain serves as an important political lesson for strategists. After the Labor Party established the National Health Service after World War II, supposedly conservative workers and low-income people under religious and other influences who tended to support the Conservatives were much more likely to vote for the Labor Party...

Which is of course why Conservatives here in Canada, while unable to attack it too blatantly undermine universal health care at every opportunity.