TPM has this video of Sen. Joe Lieberman explaining his opposition to Obama's "Public Option" (aka the Destruction of Private Medicine Act of 2009).
"If we create a public option, the public is going to end up paying for it." should be the mantra of anyone who opposes this plan. The CBO has calculated that the cost of the plan will be $1 trillion over the next 10 years, and the CBO almost always guesses far too low.
Proponents of the plan argue that the plan "pays for itself," which in government terms means we'll all end up paying for it. The problem with the federal government getting involved in the insurance business even if it claims to "play by the same rules as the insurance companies" is a fallacy.
The government program doesn't have to turn a profit. If an insurance company runs out of money, it goes out of business. If the government program runs out of money, it prints more money.
The Cato Institute put together this critique of the Obama plan after the Obama informercial on health care.