As Thompson signed the agreement, his farewell party was starting a floor above his office in the Hubert H. Humphrey Building. Kennedy and Romney joined the festivities, cracking up the crowd with an impromptu standup routine as "the odd couple" while sharing a stage for the first time since the debates in the 1994 Senate race.

Over the next 15 months, Romney pursued an innovative approach: Require all who could afford insurance to buy it; use $1 billion set aside for free hospital care for the uninsured to subsidize coverage for the working poor; and create an agency to help market affordable health plans from private insurers.

Meanwhile, the Senate crafted a more incremental plan and the House advanced one that added a payroll tax on employers that did not provide health insurance.

As a legislative standoff rolled into 2006, Romney became anxious. One Sunday morning in January he hand-delivered letters to the homes of House Speaker Salvatore F. DiMasi in Boston's North End and Senate President Robert E. Travaglini in East Boston, urging them to compromise.

DiMasi wasn't home. Travaglini was, and he cackles as he recalls the sight of Romney at his door. Romney rarely lobbied lawmakers, let alone made house calls.

"How often does the governor ring your bell on a Sunday morning to deliver personally a letter?" he said with a laugh.

After months of hard bargaining by Romney aides, legislators, advocates, business leaders, insurers, and health-care providers, a compromise bill emerged from the Legislature in early April with a goal of providing coverage for virtually all of the state's more than 400,000 uninsured. Gone was the payroll tax in the House version. In its place was an annual fee of $295 per person for companies that had 11 or more employees and didn't provide a health plan.

At first, Romney voiced no objections to the fee, which some conservatives saw as a new tax. But in an April 11 op-ed article in The Wall Street Journal, Romney said he would take "corrective action."

Democrats who were invited to Romney's bill-signing extravaganza the next day at Faneuil Hall felt betrayed, furious that Romney had vetoed the "employer assessment" and seven other sections of the 145-page bill.

Politically, Romney was able to have it both ways. With a stroke of his pen, the would-be presidential candidate signed a landmark law and used his line-item veto to wash his hands of something resembling a tax increase to help pay for it. The vetoed parts of the bill were certain to be overridden in both the House and Senate anyway.

More than a year later, DiMasi is still angry, saying Romney's vetoes, if let stand, would have "torn the guts out of the bill. He was protecting himself, knowing he was running for president."