(CNN) – Republicans wouldn't say definitively on Sunday whether presumptive GOP nominee Mitt Romney was facing a problem with voters skeptical about his health care law in Massachusetts, which bears resemblance to President Barack Obama's measure.
Sen. Mitch McConnell, the top Republican in the U.S. Senate, said simply that Romney would "have to speak for himself" when it comes to the Massachusetts law, which members of Obama's administration have said was the model for their own legislation.
McConnell made a point of referring to Obama's penalty for people who do not obtain health insurance as a "tax," a term made possible by the Thursday Supreme Court decision to uphold the mandate under Congress' power to levy taxes.
"I can tell you that every single Democratic senator voted for this tax increase," McConnell said on "Fox News Sunday."
The tax penalty in the president's health care law, which will be administered through the Internal Revenue Service, is similar to a provision in the reform plan passed in Massachusetts under then-Gov. Mitt Romney.
In a 2009 interview with CNN, Romney explained how the Massachusetts health care mandate worked. If a state resident decided to forgo health insurance when he or she could afford it, Romney said, that person would face the loss of a tax exemption. In other words, he or she would be assessed a tax penalty.
"There are a number of ways to encourage people to get insurance and what we did, we said: 'You're going to lose a tax exemption if you don't have insurance,'" Romney told CNN in the interview.
The former Massachusetts governor said the mandate was necessary to achieve universal coverage in the state.
In order to qualify for the tax exemption, Romney added, "You've got to have health insurance, because we want everybody in the system. No more free riders."
During the interview Romney held up his health care law as a model that "could inform Washington on ways to improve health care for all Americans."
Since then, Romney has said repeatedly his plan was meant for Massachusetts only.
On Sunday, Louisiana Gov. Bobby Jindal backed Romney's point, saying the GOP presidential candidate had always been opposed to a national mandate.
"Look, states are different," Jindal said. "The Founding Fathers intended states to be a laboratory of experimentation. I come from one of the most distinct cultural states in the entire country. Mardi Gras is great for Louisiana - may not work as well in Vermont and other states. The idea is, what works in Massachusetts may not work in another state."
Republican House Speaker John Boehner made a similar argument, saying Romney's law was "an issue that was in Massachusetts."
"One state. That's why we have 50 different states. They're laboratories of democracy," Boehner said.
Boehner wouldn't say, however, if Romney was facing a credibility problem with voters who regard his Massachusetts law as the same as Obama's federal law.
Instead, Boehner reiterated that Romney was just as committed to repealing Obama's health care law as any Republican.
"Gov. Romney, just like all the rest of us Republicans in Washington, are going to work to repeal Obamacare, and our resolve is stronger than ever with the passage, or the approval of the Supreme Court."
CNN National Political Correspondent Jim Acosta contributed to this report.