The so-called “public plan option” has emerged as one of the most controversial elements of the emerging health-care reform effort in Congress. Critics have argued that it would pave the way for a full government takeover of American health care.

They’re right, as rigorous analysis from The Lewin Group, a health policy consulting firm, shows. Lewin analysts have modeled what a new, price-controlled, government-run option would do to insurance enrollment in the United States. Their conclusions are alarming. If the new plan paid the same fees as Medicare, private, job-based insurance would effectively cease to exist, and some 118.5 million Americans who were previously in private plans would end up in government-run insurance. It would only be a matter of time before American health insurance resembled the single-payer models of the United Kingdom and others.

Lewin’s analysis is summarized in a series of extremely useful PowerPoint slides (available here in PDF format), which were the basis for a presentation to the Republican staff of the Senate Finance Committee last December.