(CNN) -- For Mitt Romney, it's not just a question -- it's more like a campaign illness he'd like to cure once and for all.
"I was hoping I would be asked that question. Great. It's about time," Romney joked at a recent GOP forum in New Hampshire. The question, of course, was about the health care reform bill Romney signed into law as governor of Massachusetts in 2006.
"Ours is an experiment. Some parts didn't work," he explained to the crowd.
What many tea party conservatives can't stand about the Massachusetts health care law dubbed "Romneycare" is the plan's individual mandate that requires people in that state to buy medical insurance or pay a tax penalty.
The Wall Street Journal in an editorial on Thursday slammed Romney's reluctance to reject the individual mandate.
"If he does not change his message, he might as well try to knock off Joe Biden and get on the Obama ticket," the newspaper wrote.
Republicans and Democrats alike see "Romneycare" as the prototype for what conservatives deride as "Obamacare." A similar mandate in the president's health care law is being challenged in federal courts.
It's a tight box for Romney: He must convince his fellow Republicans to look past the very health care reform provision that's at the heart of those court challenges.
"The individual mandate is a deal-breaker. People do not want to see government dictating that they purchase what is a private product. We think that's a disaster," said Tim Phillips, president of Americans for Prosperity. The group is a prominent tea party organizer that also happens to be led by libertarian billionaire David Koch.
Phillips is one of countless tea party activists who want to hear Romney reject the mandate. "I think it will be difficult for a lot of voters to get around if the individual mandate is not repudiated," Phillips said.
That would be tricky for Romney who has repeatedly defended such mandates as a way to get the uninsured into the health care system.
"In order to get the tax exemption that you would normally get, you have to have health insurance because we want everyone in the system. No more free riders," Romney said in a 2009 interview with CNN.
In the same interview, Romney suggested that parts of the Massachusetts experiment could serve as a model for national health care reform.
"I think there are a number of features in the Massachusetts plan that could inform Washington on ways to improve health care for all Americans," Romney said.
Democrats have quotes like that cued up for the 2012 campaign.
In a February speech to the National Governors Association, Obama announced his administration's plan to give states more flexibility in implementing the new national health care law.
The president worked in a dig at Romney.
"I agree with Mitt Romney, who recently said he's proud of what he accomplished on health care in Massachusetts and supports giving states the power to determine their own health care solutions. He's right," Obama said.
"Mr. President, why didn't you call and ask how it worked," Romney responded at that GOP forum in New Hampshire.
It will be a hard sell for Republicans.
Former Arkansas governor and potential 2012 rival Mike Huckabee has described "Romneycare" as "socialized medicine."
Romney has said repeatedly the Massachusetts law is not perfect. In speech after speech, the former governor has claimed the plan was never intended as a "one-size fits all" program for the country.
"We should learn from what's working and what's not working in Massachusetts," Romney told CNN in 2009.
The former governor, who has yet to declare his candidacy for 2012, has a new health care plan that he is to release Thursday. It would repeal and replace the national health care law. Instead, states would be allowed to conduct their own experiments in health care reform.
It's a potentially defining issue for a campaign that hasn't officially launched.
"Somehow he's got to convince the tea party people that he's learned from his mistake without admitting he made a mistake. Good luck," said Larry Sabato with the University of Virginia Center for Politics.
Romney's staff says don't expect an apology for "Romneycare." After all, this is a man whose latest book is entitled "No Apology."