|Would the public plan have access to taxpayer funds unavailable to private plans?|
If the answer is yes, then the public plan would not offer honest competition to private plans. The taxpayer subsidies would tilt the playing field in favor of the public plan. In this case, the whole idea of a public option seems to be a disingenuous route toward a single-payer system, which many on the left favor but recognize is a political nonstarter.
But, Greg, it is the private insurers who are currently receiving giant taxpayer subsidies in the form of Medicare. The majority of people who are old -- i.e. the ones who cost by far the most -- are paid for by the gub'ment. So if you want private insurance to compete on an equal playing field, then they too need to take all comers and not drop them when they change jobs or retire.