On his own road to the White House, Romney faced challenges from within his own party on the health care issue.
When governor of Massachusetts, he signed a 2006 health care law which included an individual mandate. He wasn't helped by the Obama administration, which said it drew from the Massachusetts law in crafting its own plan. The candidate defended "Romneycare" as a state-level solution for his state's issues, arguing states should design their own health care systems because a one-size, nationwide solution would not fit all.
Poll: Opinions mixed
The most recent CNN/ORC poll showed Americans are as split as Washington over the law. The January survey shows that 51% favor most or all of the proposals, while 44% oppose most or all elements of the law. Those numbers are reversed from 2011, when only 45% were in favor and 51% opposed.
A Bloomberg poll conducted in February found 55% thought health care costs would become worse in the next 12 months. Only 22% said health care costs would get better, and 21% expected costs to remain about the same.
The law remains unpopular in Republican circles, giving those who vocally oppose it an audience in the GOP.
"Ted Cruz is putting down some markers," Republican strategist and CNN contributor David Frum said Friday on CNN's "The Situation Room."
"There is a struggle to define who is going to be the next leader of the Republican Party, and a lot of people who have emerged early are people who have one strike or another against them," he said. "Rand Paul, they're too exotic. Another case is they may not have the force of character, but Ted Cruz has the toughness and brains, and he represents an important fundraising state. He is putting down his marker to be at least a Senate leader, maybe more."
Much of the law takes effect next year
There are, however, a few Republican leaders supporting portions -- but only portions -- of the law taking effect.
At least eight Republican governors have said they support an expansion of Medicaid, the health coverage program for the poor, which is included in the health reform law. The Supreme Court ruled the federal government could not compel the states to accept this portion of the law.
Some have said they only support the expansion for three years, when the federal government funds the entire cost. After that, the federal government will fund 90% and the states 10% of the program.
Governors who have accepted the program include New Jersey's Chris Christie and New Mexico's Susana Martinez, both of whom are thought by some as potential White House contenders.
Arizona's Jan Brewer, Michigan's Rick Snyder, Nevada's Brian Sandoval, North Dakota's Jack Dalrymple and Ohio's John Kasich have also voiced support for the program.
Gov. Rick Scott of Florida said he would accept it, but his state legislature voted not to.
The Medicaid expansion is one of several health care changes set to take effect next year, including the law's most high-profile elements, including the ban on dropping patients with pre-existing conditions, ban on annual benefit limits and the health insurance exchanges. About half of the states have said they will conduct their own exchanges; exchanges in the other states will be run by the federal government.
Federal agencies are already deep into the complicated rule-making process which will stand behind the actual law.
Senate Minority Leader Mitch McConnell, a Kentucky Republican, wheeled out this week a hand truck stacked with documents that towered over him.
"You know nothing sums up all the excesses of the Obama Administration like Obamacare," he said. "For example, these are the first regulations: 20,000 pages, 7 feet tall, and they're just getting started. Everything they promised about Obamacare isn't coming true."
And as people around the country start to navigate the law, expect the arguments for and against the law from both sides of the aisle to continue.