COLUMBIA — Uninsured South Carolinians can begin signing up for health coverage on Tuesday through the online marketplace created under the federal health care overhaul, but many residents may have no idea how to do that in a state run by Republicans who have actively opposed the process.

South Carolina is among 36 states that opted against running its state exchange, leaving that to the federal government. So it’s spent no money to advertise it. Still, hundreds of thousands of uninsured South Carolinians are expected to sign up for health insurance, and some state agencies have geared up to help.

The state’s Medicaid agency has expanded its existing call center for Medicaid-eligible residents and launched a 2-1-1 center to answer health overhaul questions, complete with a team ready to help residents sign up.

Asked why, director Tony Keck made clear his agency’s assistance is not due to any support for the Affordable Care Act.

“We expect increased calls to our Medicaid call center by frustrated South Carolinians, and we will do our best to direct them to the right place to get an answer,” he said.

Organizations recruited by the federal government to help people navigate the process appear to largely still be in the planning stages in South Carolina. Officials of both nonprofits and insurers said they expect chaos and confusion. But Melanie Colclough, deputy director of The Benefit Bank of South Carolina, said people are putting too much emphasis on opening day.

“You have some time to actually shop and understand everything,” said Colclough, whose group is partnering with a company that received a federal outreach grant. “You don’t have to pull the trigger and go on Oct. 1.”

Beginning in 2014, people who don’t have health insurance will have to pay a penalty. Enrollment through the exchange begins Tuesday, but people have until Dec. 15 to sign up for health coverage that starts Jan. 1. They have until March 31 to avoid the penalty.

“A lot of the mystery will be unveiled Oct. 1,” Colclough said. “It’s OK. Everybody can breathe now.”

In South Carolina, three insurance companies will offer a total of 52 plans to individuals and families over the exchange, according to the state Department of Insurance. That includes eight “catastrophic” plans, which the federal law limits to those under 30 and some low-income residents.

Participating insurers are Blue Cross and Blue Shield of South Carolina; Consumers’ Choice Health Plan, a nonprofit cooperative; and Coventry Health Care of the Carolinas. Both Blue Cross Blue Shield and Consumers’ Choice are offering plans statewide. Coventry’s range is unclear. A Coventry spokeswoman said parent company Aetna would call The Associated Press to answer exchange questions, but no one called.

Blue Cross Blue Shield will offer about 20 plans. Its marketing effort includes opening as many as seven retail stores by the end of 2014, adding to those opened in Mount Pleasant and Greenville. It is also sending a 40-foot mobile unit, with five agents aboard, to large sporting events and festivals across the state, as well as small communities that can’t support a store. And the company’s hired about 15 people to help residents sign up for its plans, said Terry Peace, a company vice president.

Consumers’ Choice is among 24 co-ops nationwide created by the federal law. Limited by how it can use a federal loan to market its eight plans, outreach involves a team of six people talking at churches and community forums, said spokeswoman Adrian Grimes.

“We were designed to create competition and drive down cost,” she said.

On average, South Carolinians will be able to pick from 26 plans, depending on where they live, according to a federal report released Wednesday.

Outside of catastrophic plans that protect from worst-case scenarios, plans must fall within four tiers: bronze, silver, gold and platinum. The benefits are the same, but the cost-sharing varies, with bronze requiring the highest out-of-pocket expenses in deductibles and co-pays.

No company is offering platinum-level options to individual buyers in South Carolina, according to state officials.

Specifics of South Carolina’s plans – including premiums, cost-sharing and provider access – aren’t being made public until goes live Tuesday. The Obama administration’s report said the sticker price in South Carolina for a midrange plan will be $339 a month on average, before federal subsidies that work like upfront discounts.

That in-state average for a benchmark policy known as the “second-lowest-cost silver plan” is $11 more than the national average. But averages can be misleading. What residents pay for premiums will vary widely, with factors including family size, age, income and tobacco use. Catastrophic plans don’t qualify for subsidies.

Those helping the uninsured enroll include “navigators,” who must complete 20 to 30 hours of training and pass an exam to be certified. They can determine whether people are eligible for subsidies and help them through the online process, but they can’t suggest which plan to pick.

Last month, the Obama administration awarded three groups a total of $2 million in federal navigator grants for outreach in South Carolina.

The largest grant of more than $1.2 million went to DECO Recovery Management, which is working with the Benefit Bank. No one from the Maryland-based company returned messages left by the AP over the past week. On Thursday, someone answering the phone said people were still in training.

The Benefit Bank, created in 2009 to help people secure various social services, has volunteer counselors in roughly 500 locations across the state’s 46 counties. But DECO is in charge of the navigator program.

“This was a no-brainer for DECO to partner with us,” Colclough said. “We were already in the trenches all over South Carolina.”

The Columbia-based Cooperative Ministry received $508,300 to target uninsured people in eight counties, though the group hopes to cover more. When fully staffed, the charity expects to have between 30 and 45 navigators. As of Friday, 11 were certified and five others had completed their training, said program director Wanda Pearson.

Appointments will be available beginning the second week of October. Navigators will spend the first week familiarizing themselves with the exchange, she said.

The Beaufort County Black Chamber of Commerce received $234,100. Six of its seven navigators are certified. To reach people across eight counties, they will work with “certified application counselors” – volunteers who receive five hours of training. Help will largely be offered through church functions and other community events, said Larry Holman, the chamber’s president.

The state’s hospitals are working with the navigator groups and the 19 health clinics that received a combined $2.4 million for outreach efforts. Hospitals are interested in getting staff trained as “certified application counselors,” but so far it appears none have, said Shalama Jackson, spokeswoman for the state Hospital Association.