The LEGISLATURE did.
At least that's what the Wiki says:
In Fall 2005, the House and Senate each passed health care insurance reform bills. The legislature made a number of changes to Governor Romney's original proposal, including expanding MassHealth (Medicaid and SCHIP) coverage to low-income children and restoring funding for public health programs.
But here's Mitt on insuring children:
“[D]on’t forget — I got everybody in my state insured,” Romney told NBC. “One hundred percent of the kids in our state had health insurance. I don’t think there’s anything that shows more empathy and care about the people of this country than that kind of record.”
Um, no Mitt, YOU didn't. Your DEMOCRATIC LEGISLATURE did.
Mitt also vetoed the fuck out of the legislation. ALL vetoes had to be overridden to make the health care plan MA now has.
On April 12, 2006, Governor Mitt Romney signed the health legislation. Romney vetoed eight sections of the health care legislation, including the controversial employer assessment. Romney also vetoed provisions providing dental benefits to poor residents on the Medicaid program, and providing health coverage to senior and disabled legal immigrants not eligible for federal Medicaid. The legislature promptly overrode six of the eight gubernatorial section vetoes, on May 4, 2006, and by mid-June 2006 had overridden the remaining two.
Stop lying to the voters, Mitt. Nobody trusts a word that comes out of you any longer. Taking credit for trying to gut the program.
America deserves better, Mitt.