Romney defending his health care bill in 2011 (Carlos Osorio/AP)Mitt Romney has distanced himself from the health care reform bill he signed as governor of Massachusetts amid criticism that the law bears more than a passing resemblance to Obamacare, which he's repeatedly pledged to repeal if elected in November.

But a series of emails obtained by the Wall Street Journal reveals Romney was actively engaged in negotiating the specifics of the 2006 Massachusetts bill and that he and his top aides championed a provision identical to one in President Barack Obama's law requiring individuals to have or buy health insurance.

The so-called individual mandate is at the heart of most conservative criticism of Obama's health care law, with many Republicans calling the provision unconstitutional. But in 2006, emails obtained by the Journal under a public records request show, Romney and his top aides pressed for an individual mandate even when Massachusetts Democrats weren't yet embracing such a proposal.

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According to the emails, Romney personally drafted a Wall Street Journal op-ed that defended the individual mandate. Romney's draft, slightly different from the final version that was published, insisted taxpayers ultimately foot the bill when the uninsured seek health care—an argument that has been echoed by the White House in defending Obama's bill.

"Either the individual pays or the taxpayers pay. A free ride on government is not libertarian," the published op-ed said.

But according to a draft obtained by the Journal, Romney went one step further, arguing, "An uninsured libertarian might counter that he could refuse the free care, but under law, that is impossible—and inhumane."

Romney has defended the Massachusetts law by arguing that he did the right thing for his state. In campaigning for a repeal of Obama's law, Romney has rejected the "one size fits all" approach and argued that it should be up to individual states to determine how to handle health care coverage.

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But Romney has said very little about the individual mandate. A Wall Street Journal op-ed published in March 2011 called him "compromised and not credible" because of his support of the mandate in Massachusetts and described him as "Obama's running mate." In a subsequent letter to the editor, Romney defended the bill, but did not specifically respond to the paper's argument that his support of the mandate was a violation of conservative principals.

Romney's campaign did not respond to a request for comment about the emails.