President Barack Obama based his health care law directly on a similar law passed in Massachusetts when Republican presidential candidate Mitt Romney was governor, an NBC News investigation released on Tuesday found.

According to White House visitor logs, three health care experts who advised Romney in 2006 met with senior officials in the Obama administration on at least a dozen occasions in 2009, when Obama was developing his health care plan.

Obama himself presided over one of the meetings. Others were led by Lawrence Summers, Obama's chief economic advisor; Peter Orzag; Obama's budget director; and Nancy-Ann DeParle, the president's chief adviser on health care.

The White House wanted to lean a lot on what we'd done in Massachusetts, Jon Gruber, an economist at the Massachusetts Institute of Technology and one of the experts who advised Romney, told NBC. They really wanted to know how we can take that same approach we used in Massachusetts and turn that into a national model.

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Romney has come under fire from his Republican opponents for signing the Massachusetts law, which critics refer to disparagingly as Romneycare, just as they refer to the national law as Obamacare.

Romney has tried to parry the attacks by characterizing the Massachusetts law as beneficial for his state but inappropriate on a national scale. He has called Obama's law a one-size-fits-all national health care system and vowed to repeal it as president.

He does me the great favor of saying that I was the inspiration of his plan. If that's the case, why didn't you call me? Romney said last April in response to earlier suggestions that Obama had based his plan on the Massachusetts law. Why didn't you ask what was wrong? Why didn't you ask if this was an experiment, what worked and what didn't?

If Obama had consulted him, I would have told him, 'What you're doing, Mr. President, is going to bankrupt us,' Romney said.

But the experts who advised Romney do not seem to have advised Obama against basing national policy on the example set by Massachusetts.

2006 Massachusetts Health Care Law Viewed as Historic, Innovative

When it was passed in 2006, the Massachusetts law was heralded as a historic breakthrough, and it was seen as one of the crowning accomplishments of Romney's term as governor. Romney threw his full support behind the law, and, interestingly, he was the biggest proponent of an individual mandate: the most controversial provision of the national health care law.

The individual mandate requires every citizen to buy health insurance to avoid a tax penalty. Romney's advisers -- the same experts who met with White House officials in 2009 -- were hesitant about that provision. But according to Gruber, the MIT economist, Governor Romney clearly stated that he believed without an individual mandate, healthy people could just free-ride on the system.

Interestingly, although Romney has maintained adamantly on the campaign trail that he never intended the Massachusetts health care plan to become a model for national policy, the first edition of his book, No Apology, said of the plan, We can accomplish the same thing for everyone in the country. He deleted that line in the paperback edition.

Texas Gov. Rick Perry, one of Romney's opponents for the Republican presidential nomination, released an attack ad on Monday that highlighted the deletion of that line.

When it comes to government-mandated health care, there is no difference between Mitt Romney and President Obama, a spokesman for Perry said in a press release.

Gruber argued that, despite Romney's attempts to distance himself, his efforts in Massachusetts contributed in a major way to the passage of the national health care law.

I think he is the single person most responsible for health care reform in the United States, he told NBC. I'm not trying to make a political position or a political statement -- I honestly feel that way. If Mitt Romney had not stood up for this reform in Massachusetts ... I don't think it would have happened nationally. So I think he really is the guy with whom it all starts.

He also largely dismissed the differences Romney has highlighted between the Massachusetts plan and the national plan. Romney has said, for example, that the law he passed did not require any tax increases, as Obama's plan did -- but that was because Massachusetts received federal funding to cover the cost.