Harvard economics professor Greg Mankiw in the New York Times on the perils of the public option in health care reform:

An important question about any public provider of health insurance is whether it would have access to taxpayer funds. If not, the public plan would have to stand on its own financially, as private plans do, covering all expenses with premiums from those who signed up for it.

But if such a plan were desirable and feasible, nothing would stop someone from setting it up right now. In essence, a public plan without taxpayer support would be yet another nonprofit company offering health insurance. The fundamental viability of the enterprise does not depend on whether the employees are called “nonprofit administrators” or “civil servants.”

In practice, however, if a public option is available, it will probably enjoy taxpayer subsidies. Indeed, even if the initial legislation rejected them, such subsidies would be hard to avoid in the long run. Fannie Mae and Freddie Mac, the mortgage giants created by federal law, were once private companies. Yet many investors believed — correctly, as it turned out — that the federal government would stand behind Fannie’s and Freddie’s debts, and this perception gave these companies access to cheap credit. Similarly, a public health insurance plan would enjoy the presumption of a government backstop.

Such explicit or implicit subsidies would prevent a public plan from providing honest competition for private suppliers of health insurance. Instead, the public plan would likely undercut private firms and get an undue share of the market.