Mitt Romney on Wednesday said requiring all Americans to buy health insurance amounts to a tax, contradicting a senior campaign adviser who days ago said the Republican presidential candidate viewed President Barack Obama's mandate as anything but a tax.

"The majority of the court said it's a tax and therefore it is a tax. They have spoken. There's no way around that," Romney told CBS News. "You can try and say you wish they had decided a different way but they didn't. They concluded it was a tax."

Romney's comments amounted to a shift in position. Earlier in the week, senior adviser Eric Fehrnstrom said Romney viewed the mandate as a penalty, a fee or a fine - not a tax.

The Supreme Court last week ruled that the federal requirement to buy health insurance or pay a penalty is constitutional because it can be considered a tax. The requirement is part of the broad health care overhaul that Obama signed into law in March 2010.