COLUMBIA - Would an expansion of Medicaid under the federal health-care law help or hinder South Carolina's finances? Depends who you ask.

Strains of disagreement are building against the backdrop of a campaign by Gov. Nikki Haley's administration to build opposition to an expansion.

Generally opposed by Republicans and favored by Democrats, the debate over whether to expand the Medicaid program in the states is set to play out in many statehouses across the country. That's because a June Supreme Court ruling made the extension of coverage optional.

In the Palmetto State, advocates for the expansion contend Haley's administration is emphasizing the costs and underselling offsetting economic benefits of an expansion.

"They are just cranking the numbers up, throwing every piece of cheese and baloney they can on the scale," said John Ruoff, a Columbia health-care consultant.

"It's partisan politics, pure and simple," added Frank Knapp, a longtime supporter of the health-care law and president of the South Carolina Small Business Chamber of Commerce.

With many of the details of how various parts of the expansion would work still unclear, the numbers battle has taken on heightened importance.

Lawmakers are meeting with Haley's S.C. Department of Health and Human Services and beginning to formulate their stances on whether or not the state should expand Medicaid and take the huge pot of federal money that would come with it.

On the line is health insurance for an estimated 350,000 to more than 600,000 needy South Carolinians.

Haley's Medicaid Director Tony Keck said the agency believes the projections it's publicizing, based on an April report by actuarial firm Milliman, are accurate.

He convened a meeting in Columbia in July for health care leaders to address the numbers.

Keck said there are more projections to come, calling it an "open process." "I've got to get a number to the Legislature," he said. "If I don't get a good number to the Legislature, I'll lose my job."

There is dramatic variance in that number.

Based on the Milliman report, the state health department is estimating the cost of expansion to the state could be as much as $2.4 billion for the first six years from fiscal years 2014-20.

The Medicaid agency projects the cost to increase even more after that period due to a reduced federal match.

At the other end of the spectrum, a 2011 study of the federal health-care overhaul's impact on states by the nonpartisan but liberal-leaning think tank the Urban Institute estimated South Carolina could save between $59 and $678 million in state spending from 2014-19.

The institute's report includes a broad spectrum of state-level estimates of the health law's financial impact. The Milliman report mainly looks at the cost of the Medicaid expansion for the state health department budget.

In large part, the projections are so different because of differences in the assumptions that are factored in, such as how many people who are currently eligible for Medicaid but not enrolled would sign up in the coming years.

Ruoff said Milliman's estimates for participation by those South Carolinians are too high. Rob Damler, the report's author, and Keck said the report utilizes the best data available.

There's another factor at play in the discrepancy between the reports. Milliman factors in the cost to the state of the first six months of a 10 percent match for the expansion that begins in 2020. The Urban Institute's estimates cut off at the end of 2019.

Keck said critiques of the state's projections are an important part of the ongoing process of obtaining an accurate picture of the expansion's impact.

"I think this conversation is perfectly appropriate," he said. "That's why we're not afraid to make the numbers as public as possible."

Reach Stephen Largen at 864-641-8172 and follow him on Twitter @stephenlargen.