A cache of internal emails published in the Wall Street Journal illuminates how Mitt Romney made a mandate to purchase health insurance the linchpin of Massachusetts' sweeping 2006 health care law.

Republicans have uniformly attacked the individual mandate contained in President Obama's health care overhaul, denouncing the requirement as a symbol of the federal government overreaching. That has exposed Romney, the presumptive Republican presidential nominee, to criticism.

Romney has sought to distance himself from the Massachusetts law, saying it was a state solution that should not be imposed on the entire country. But critics on the right and Obama's re-election team have pushed back, charging that the Massachusetts law was a model for the federal version.

The emails show the extent to which Romney and his team stressed the individual mandate as a market-friendly alternative to a government-run system, reflecting the prevailing logic on the right at a time when conservative stalwarts like the Heritage Foundation supported the mandate.

In February of 2006, an aide to then-governor Romney sent an email to him and his inner circle discussing a health care reform plan State Senate President Robert Travaglini, a Democrat, was quietly working on.

It is unclear that the plan adopts an individual mandate, Tim Murphy wrote. We must have an individual mandate for any plan to work.

Several days later, Eric Fehnstrom, currently serving as a top adviser to Romney's presidential campaign, noted that the Senate was poised to add an individual mandate to a health care bill it was debating.

Given that's a central part of Romney's proposal, I would think he, or at least Tim Murphy, would want to weigh in. Fehnstrom wrote. What do you think?

A series of exchanges center around an op-ed Romney was writing for the Wall Street Journal. At the start of the piece, Romney recounted being advised to seek universal health insurance coverage and worrying about raising taxes and a Clinton-style government takeover. The alternative, Romney wrote, was to have everyone obtain insurance.

Some libertarian friends balk at an individual mandate. But is it libertarian to insist that government pick up the tab for those without insurance or means to pay? Romney wrote. An uninsured libertarian might counter that he could refuse the free care, but under law, that is impossible -- and inhumane.

Some of the ideas the op-ed went on to tout are also parts of the Affordable Care Act. Both bills give financial assistance to people who are too poor to purchase their own insurance but not poor enough to qualify for Medicaid. 

Because health insurance will now be affordable and subsidized, we insist that everyone purchase health insurance form one of our private insurance companies, Romney wrote.

As Romney prepared to sign the bill, his staff had a lengthy back-and-forth about his decision to veto a measure, pushed by Senate Democrats, that would have imposed a $295 per person annual fine on companies that did not insure their employees. Romney was willing to extend an existing $62 fee as a compromise, but some of his team worried that even mentioning that amount would suggest hostility toward business. Clearly, the bill was designed to accommodate, not threaten, the industry.

On April 12, 2006, the day he signed the bill, Romney wrote a note to top aide Thomas Trimarco thanking him for his role in shepherding the legislation through.

You have made a huge difference, Romney wrote, for me and for hundreds of thousands of people who will have healthier and happier lives.