"The ACA's penalties for not purchasing insurance are less than those under Medicare Parts B and D and the proposed [Republican] Patient Choice, Affordability, Responsibility, and Empowerment Act (PCARE)," said the release.

The rationale is pretty much the same for all three: If too many individuals were allowed to opt out of coverage with no consequences, insurance premiums would skyrocket and the attempt to reform the system would collapse.

Each of the plans approaches the mandate from a slightly different perspective, the institute says.

Obamacare penalizes those who go bare for more than three months in a year. Penalties can be avoided by acquiring coverage in the subsequent enrollment period.

The GOP's proposal, PCARE, requires folks to have health insurance for at least 18 months before they can be assured of coverage via a private non-group insurance policy. If they fail to follow the law, they face purchasing more expensive coverage or paying out-of-pocket for all medical services.

Medicare Parts B and D sock coverage-less individuals with premium surcharges once they acquire insurance.

"Authors of legislation that bars insurers from denying coverage to people with pre-existing conditions understand that healthy people need incentives to maintain insurance. This is necessary to keep premiums affordable and stable," says Linda Blumberg, a senior fellow at the Urban Institute and a report coauthor.

"The individual mandate is not a Republican or Democratic idea. There is a growing consensus that a mandate is needed in coverage expansion programs, yet there are differences on the appropriate levels of the penalties and the populations to which they should apply."