From TPM here. I really don't think people want to be forced into dealing solely with the for-profit insurance companies. They have their reasons.
You heard politicians mentioning the role of private insurance companies in Switzerland's health care system (it ain't so great). This is from Wikipedia:
In Switzerland, compulsory health insurance covers the costs of medical treatment and hospitalization of the insured. The Swiss healthcare system is a combination of public, subsidized private and totally private healthcare providers, where the insured person has full freedom of choice among the providers in his region. Insurance companies independently set their price points for different age groups, but are forbidden from setting prices based on health risk. In 2000, Switzerland topped all European countries’ health care expenditure when calculated as per capita expenditure in US dollar purchasing parity terms. 
The Swiss health care system is interesting as it was the last for-profit system in Europe. In the 1990s, after the private carriers began to deny coverage for pre-existing conditions—and when the uninsured population of Switzerland reached 5%--the Swiss held a referendum (1995) and adopted their present system.
(Emphasis added.) (Health care in the U.S. is even more expensive than that. It's the most expensive in the world, and we have over 46 million people uninsured, or over 15% of the population. (Source).)
From The New York Times here:
Swiss insurance companies offer the mandatory basic plan on a not-for-profit basis, although they are permitted to earn a profit on supplemental plans.
Our health insurance companies aren't going to offer that here. That's why we need the public option.
[Sent this to Sen. Reid tonight.]