The Minnesota State Fair has become the latest battleground over Obamacare.

A new billboard on Snelling Avenue near the fairgrounds is urging people to “refuse MNsure,” the state’s new insurance exchange that is central to implementing the federal health law.

Meanwhile, the state plans to kick off its major MNsure marketing campaign at the Great Minnesota Get-Together later this month.

The dueling messages will only escalate amid a fierce national debate, said George John, chairman of the marketing department at the University of Minnesota Carlson School of Management.

“It’s going to be a food fight,” he said. “This is such a huge thing with so many moving parts, you’re going to see all kinds of little turf wars breaking out all in sorts of domains. It’ll have politics in it, it’ll have marketing in it. … We haven’t seen anything like it since Medicare started in 1965.”

The Minnesota-based Citizens’ Council for Health Freedom, a longtime opponent of exchanges and the Affordable Care Act, put its billboard up on Wednesday in hopes of catching the eye of the 1.7 million Minnesotans who visit the fair each year, said Twila Brase, the group’s president and co-founder.

It will remain through the end of the State Fair on Labor Day, promoting a website and ­message to encourage people not to use the MNsure exchange.

“The exchange is the Achilles’ heel of Obamacare,” Brase said. “Without exchanges, Obamacare can’t be implemented.”

John Reich, a MNsure spokesman, hadn’t seen the billboard but said opposition to the exchange wasn’t unexpected.

“We’re charged with finding a way to deliver high quality, affordable health insurance for Minnesotans,” he said. “That’s what we’re focused on doing right now.”

On Friday, the Minnesota Department of Commerce said that all the insurance companies that will offer policies on MNsure will publicly release policy rates and information on Sept. 6 — nearly a month earlier than planned.

The insurers agreed to the earlier release after the Commerce and Health Departments asked for more transparency for consumers.

Minnesota is one of 16 states and the District of Columbia to build an online exchange to serve those on public programs as well as small businesses and residents who don’t get health insurance at the workplace. The MNsure exchange opens Oct. 1 and state officials project that 1.3 million residents will eventually use it to comparison shop for health plans.

Officials have not disclosed details of what their marketing program will include.

But as the launch date approaches, Brase said her group may put up more critical billboards but declined to offer specifics. Her group put up four billboards last March as lawmakers debated a bill to create a Minnesota-built exchange.

Aside from privacy concerns, Brace argues that too many insurers have formed narrow alliances with hospitals and clinics, resulting in fewer choices for consumers using exchanges.

The billboard near the fairgrounds shows a woman with folded arms asking, “Why can’t I choose my own doctor?”

Greta Bergstrom, a spokeswoman with the community activist group TakeAction Minnesota, said the billboard offered a “misleading message” and that MNsure “has nothing to do with choosing your own doctor.”

“The billboard is a cynical ploy to scare Minnesotans away from signing up for affordable health care,” said Bergstrom, whose organization will work to sign people up for the MNsure exchange. “Minnesotans are smarter than that.”