Minnesotans are evenly divided on whether to keep or repeal the federal health care law, with likely voters split sharply along partisan lines, according to a Star Tribune Minnesota Poll.

About 46 percent of the state's likely voters say they support keeping the Affordable Care Act, whose main tenets were largely upheld by the U.S. Supreme Court this summer, while 47 percent believe the law should go.

Support was strongest among voters ages 18 to 34 and those who make less than $50,000 a year. More than eight out of 10 Democrats said the law should stay in place, while nine out of 10 Republicans back GOP presidential nominee Mitt Romney's pledge to repeal it.

About one in five voters sees health care as the most important issue in determining their vote for president, with those who support the law far more likely to name health care as their top issue. The poll of 800 likely voters, conducted Sept. 17-19, had a margin of sampling error of plus or minus 3.5 percentage points.

Bryan Dowd, a professor of health policy and management at the University of Minnesota's School of Public Health, said he's surprised that health care has hung on as a top-of-mind issue for so many Minnesotans.

But with the split so "dramatically partisan," Dowd said he wonders whether the results reflect the health care law itself or whether the measure "has become sort of a clinical marker" for the Obama administration and its critics.

"The results seem to be more about affiliations rather than a deep analysis of the likely effects of the bill on ourselves," Dowd said. "That's particularly true for this bill, most of which hasn't happened yet."

The bulk of the Affordable Care Act doesn't go into effect until 2014, when millions of uninsured people will gain coverage through an expansion of Medicaid or via state-run exchanges.

Also starting in 2014, insurance companies no longer will be able to deny coverage because of pre-existing conditions, and the controversial individual mandate, upheld by the high court, will kick in as a way to help spread the costs of covering more people.

Rob Peterson of Sturgeon Lake was among the 21 percent of poll respondents who named health care concerns as their top issue in the presidential campaign -- above jobs and the economy, taxes, government spending and the national debt.

Peterson said his family already has benefited from a provision of the law that allows adult children without access to job-based coverage to stay on their parents' health plans until they turn 26.

His son graduated from the University of Minnesota with a business major several years ago and found part-time work, but only recently landed a full-time job with good health benefits. With student loans on top of a pre-existing medical condition and prescription bills of $1,500 a month, insurance was unaffordable.

"It was very scary," said Peterson, 56, who has retired from the Department of Corrections after a 26-year career. "We wondered, 'Is he going to have to go on welfare in order to get his medication?' Fortunately, under the Affordable Care Act, he was able to be covered under my plan."

Demographic differences

Age and income were significant factors in poll respondents' views. About 57 percent of those earning less than $50,000 support the law, compared with 44 percent of those with paychecks of more than $50,000, perhaps an indication that those with higher incomes were more likely to have access to employer-subsidized health benefits.

Minnesotans in the 18-to-34 age bracket showed the strongest preference among all age groups for keeping the law, with 53 percent in support.

Among those 65-and-older, and thus likely eligible for government-paid insurance through Medicare, 49 percent said they'd like to see it repealed, vs. 43 percent who want it to remain.

Some changes to Medicare already are underway because of the health care law, including offering seniors a 50 percent discount for prescription drugs to close the "donut hole," a provision that took effect in 2011.

Romney has not said whether he would reinstate the already-enacted provisions if he were to repeal the health care law.

Either way, put Norbert Timm of Minnetonka, 79, in the repeal camp. He said he's "not particularly a Romney fan," but he'll probably vote for the former Massachusetts governor.

Timm, was a longtime employee of the former Univac, and he bristles over suggestions that Medicare or his Social Security checks are an "entitlement."

Yet he said that even after getting "excellent treatment" for his two heart attacks, an abdominal aneurism and a small stroke, his medical bills were "insignificant" because of his Medicare. Still, he doesn't believe a "Medicare-for-all" scenario is the best path for lowering costs and covering more Americans.

"I don't think our system is perfect," said Timm, who voted for Jesse Ventura for governor and considers himself a political independent. "But anytime the government gets in there, your health care is going to suffer. It's going to deteriorate."

Jackie Crosby • 612-673-7335