David Goldman/AP

LONE TREE, Colo. - Republican presidential candidate Rick Santorum today unveiled a new attack on Mitt Romney's signature health care law in Massachusetts, promising his supporters that it wouldn't be the last time they hear about it.

Speaking to about 150 people at a country club while the Republican front-runners campaigned in Florida, Santorum said "'RomneyCare' is 'ObamaCare'" and argued that President Obama would savage the former Massachusetts governor in a general election because of the similarities between their health programs.

Santorum also argued that Romney avoided raising taxes on Massachusetts residents by instead making people in other states make up for a "disproportionate" amount of Medicaid money that went back to his state.

"He says it is right for Massachusetts. No, it's not. It's government-run health care," Santorum said. "It's not how America functions. It can't be right for any state."

Santorum's argument was a wonky one. He told his supporters: "'RomneyCare' was a way to get disproportionate Medicaid dollars back in the state of Massachusetts and have all of you in Colorado pay for Mitt Romney's experiment in Massachusetts, and he could say, 'Well, I didn't raise any taxes.' Yeah he did, yours."

Critics of Romney's Massachusetts health plan have said that because it increased spending, raising the tax burden, and because much of the costs of it were covered by federal taxes, that taxpayers around the country had to cover some of the expense.

"Let me assure you that all I just told you and more, the president knows, and he will destroy Gov. Romney on the issue of 'RomneyCare,' because, in some respect, it's worse than 'ObamaCare,'" Santorum said. "Somebody says he's a businessman and he understands how business operates and he will run Washington like a business. Well, if that's the kind of business you can run out of Washington, we can do without a businessman in Washington, D.C."

The Santorum campaign has skipped the Florida primary to focus on Colorado. He announced at the campaign event that he had raised $4.2 million in January, buoyed in part most likely by a late-vote adjustment from Iowa that made him the official winner. The campaign also tells ABC News that it has $1.1 million cash on hand.

Santorum, who hasn't come close to winning a primary since the Iowa caucuses, predicted that the GOP primary race won't end any time soon.

"I know everyone focuses on the early primary states," he said. "This race is going to go on for a while, and you are going to be part of that ebb and flow. You have an opportunity to make a huge difference in lifting up a true-conviction conservative."