In Who wins if it is McCain v. Hillary? McCain v. Obama? by Mitchell Freedman, says:

“As for Obama, he remains a mirror with flowery rhetoric. People see what they want to see with him, more than many candidates. Yet, when he gets specific on matters such as health care, Obama keeps wanting to show, at least rhetorically, that he is a reliable corporate Democrat a la the Clintons.”

Obama’s health-care plan would cover less than half of the Americans without health insurance and would be voluntary—screwing any chance it has of working because the insurance pool would be out-of-balance as only sick people would volunteer to pay into the program.