http://charlespetzold.com/blog/2013/12/I-Health-Insurer.html
In 1989 and 1992, the well-known conservative think-tank The Heritage Foundation released two studies, “Assuring Affordable Health Care for All Americans” and “The Heritage Consumer Choice Health Plan,” which described approaches to health insurance that preserved the role of the free market, and hence appealed to conservative ideology. The Heritage Foundation recommendations involved requiring health insurance companies to make available policies with certain minimum standards and covering pre-existing conditions, but also require everyone to purchase health insurance, much like everyone who operates a car is required to buy automobile insurance.
It’s certainly not as elegant as single-payer “Medicare For Everybody,” but it seemed to be a reasonable conservative approach that retains a dominant role for the private-sector health insurance industry. Policies are required to cover pre-existing conditions, but there’s no anti-selection because everyone is required to buy health insurance.
Another essential guard against anti-selection is a uniformity of benefits. Medical costs that are more elective than others — such as pregnancy — can’t be optional because people planning a pregnancy would get the extra coverage before conceiving, and then drop the coverage after delivering. Such coverage must be mandatory for the system to work.
In 2006, Republican Governor Mitt Romney signed a bill implementing the Heritage Foundation approach in Massachusetts, and in 2010 the Heritage Foundation approach was adapted for nationwide use (but still administered by individual states) as the Patient Protection and Affordable Care Act, known popularly as Obamacare.