Now, Romney’s campaign finds itself in a skirmish over the issue with some fellow Republicans.

Romney’s attempt to distance himself from Mr. Obama’s law got tougher Monday when senior campaign adviser Eric Fehrnstrom veered off-message, saying the mandate in Romney’s own health care plan was a penalty, not a tax – essentially siding with the president.

“The governor believes that what we put in place in Massachusetts was a penalty, and he disagrees with the (Supreme) court’s ruling that the mandate was a tax,” Fehrnstrom said on MSNBC.

Since the court’s decision Thursday, practically every GOP leader has used the decision as proof the president’s signature legislation is a massive tax hike on Americans.

On the CBS News broadcast “Face the Nation” Sunday, House Speaker John Boehner insisted, “It’s now a tax, since the court says it’s a tax.”

Rep. Paul Ryan (R – Wis.) said on “ABC This Week” Sunday, “Believe me, if this was brought to the public as a tax, there’s no way this law would have passed into law in the first place.”

It’s a tricky spot for Romney.

From day one, he’s campaigned on a vow to scrap Mr. Obama’s health care law, but as Massachusetts governor, he signed the first individual mandate at the state level.

Some political pundits took issue with the campaign’s approach and said Romney should return his focus to the economy.

“This is a classic case where consistency and intellectual honesty is a mistake,” columnist Charles Krauthammer remarked on Fox News. “Simply accept what the Supreme Court has said. It’s a tax.”

The focus of Romney’s entire campaign has been the economy, and that’s the issue voters say they care about most. But Republicans also believe Romney could get at least a little traction due to the health care ruling, since most Americans continue to oppose at least some parts of the law.