It's not a tax. It's a penalty.

President Barack Obama's administration and its allies in Congress carpet-bombed the morning talk shows Sunday with those seven words, holding the line in a PR counter-offensive the White House has been engaging on since Friday. The push to tamp down talk of a health-care law tax is a response to the the campaign of Republican challenger Mitt Romney, who Thursday said the Affordable Care Act is raising taxes on the American people by approximately $500 billion.

Romney took that tack immediately after the Supreme Court upheld the ACA that morning. The key vote saving the law came from Chief Justice John Roberts, who ruled it was constitutional -- but only as a tax.

Some of the latest message standard-bearers included White House Chief of Staff Jack Lew, who went on ABC's This Week With George Stephanopoulos to adamantly resist the host's prodding to concede the individual mandate provision was a tax.

It's a penalty. And it's a penalty only 1 percent of Americans will be subject to, Lew said, and let's be clear about who that 1 percent is. It's people who can afford health insurance, who choose not to and then go back to the emergency room and the cost gets spread among everyone.

Across rival networks, on NBC's Meet the Press, House Minority Leader Nancy Pelosi, D-Calif., also pushed the line on host David Gregory, who had kicked off the show by saying the debate was all anyone's talking about in Washington.

It's a penalty that comes under the tax code for the 1 percent of the population who might decide they want to be free riders, Pelosi said, adding that middle-income families get, on average, $4,000 in tax breaks and tax credits as a result of the law.

What we're saying is those that take responsibility get the benefits, those that decide to be free riders get the penalty, Pelosi added.

The discussion between whether the Affordable Care Act is a tax appears to be the next big topic in the presidential race, good for at least a few more news cycles. It began on Thursday morning, following the fact the key provision of the law, an individual mandate that forces people to hold health insurance or pay a charge, was upheld by the Supreme Court under Congress' constitutional power to impose taxes -- rather than the Commerce Clause, which has been the foundation of most federal economic regulation ever since the New Deal.

The Romney campaign is also saying the act's provisions to slow the spiralling growth in Medicare spending, which the Congressional Budget Office estimates will mean $510 billion less will be budgeted for that program than if the law had not passed, should be considered a tax on the middle class.

Pundits have noted the Republican argument is the political equivalent of making lemonade out of lemons, given the fact the Supreme Court decision Thursday was roundly seen as a victory for Obama. But that hasn't stopped the Democratic administration from forcefully fighting the charge.

Before Sunday's talk show PR blitz, Jay Carney, the White House press secretary, had told reporters aboard Air Force One: It's a penalty because you have a choice. You don't have a choice to pay your taxes, right? You have a choice to buy - if you can afford health insurance. ... So if you don't buy it, and you can afford it, it is an irresponsible thing to do to ask the rest of America's taxpayers to pay for your care when you go to the emergency room.

Even the big guy himself had joined the fray, telling Stephanopoulos earlier in the week the Affordable Care Act was not a tax, even after the TV host pulled out Merriam-Webster's Dictionary and read the definition of tax to the president.

My critics say everything's a tax increase, Obama said.