BlueCross BlueShield of Tennessee will not sell insurance plans on the Obamacare exchange in the state's three largest metro areas next year, as the health care giant grapples with hefty losses and ongoing uncertainty on the marketplace.

The insurer made "an extremely difficult but necessary decision" to leave the Nashville, Memphis and Knoxville markets as it tries to manage its number of members to hit a break-even point amid three years of losses, said Roy Vaughn, chief communications officer of BCBST.

"It’s not something we want to do but we believe we must look out for the health care and financial security for all the members that we serve," Vaughn said in an interview with The Tennessean.

Tennessee Health Care Campaign, which has worked many months to help people sign up for ACA, said in a statement to 10News the announcement by BlueCross BlueShield will create confusion for many seeking health care.

Only 35 days remain until open enrollment begins, according to the campaign.

"This last minute notice by BCBS promises there will be disruption of care for those who can least afford it," Monday night's statement reads. "Shifting from one network of providers to another can itself drive people out of insurance coverage."

The BlueCross decision will reshape open enrollment, which begins Nov. 1, for people who buy individual plans in the state's three largest markets — and where Cigna or Humana, or both, are expected to sell plans. According to BCBST, 52,000 people in Nashville, 31,000 in Knoxville, and 29,000 in Memphis, will have to look to another insurer for coverage in 2017.

But there is help available for those impacted by this change.

Tennessee State Director of Enroll America, Jacob Flowers, said people can visit or call the hotline at 844-644-5443 to discuss options.

The company formally made the change to its 2017 plans in a Friday filing with the U.S. Department of Health and Human Services — roughly a month after it raised the possibility of scaling back. Earlier this summer, BCBST requested — and was granted — state approval for an average 62-percent premium increase. The rate hike is still pending federal approval.

Senate health committee Chairman Lamar Alexander said this announcement will leave some Tennesseans "scrambling" to find a new health insurance plan and is more evidence that Obamacare is falling apart.

"Short term, we need to give families the opportunity to use their Obamacare subsidies to buy a policy for 2017 outside of the exchange. Longer term, regardless of who the new president is, we need to replace Obamacare with insurance choices that allow Tennesseans to select low-cost insurance that fits their budget and their health care needs,” Alexander said in a statement.

By the end of 2016, BCBST anticipates losses from three years selling on the exchange established by the Affordable Care Act will approach $500 million.

"In our rate request we took great care to close the gap between premiums and costs. We feel like we’ve adequately addressed that, but uncertainties at the federal level could still put us in a loss position even if our experience with the group is better and our rates better reflect our medical costs," Vaughn said.

The Chattanooga-based insurer, which was the only insurer that originally planned to sell statewide, expects to shed about 112,000 people from its rolls under the change and keep about 80,000 primarily in rural areas. Shoppers in the three metro areas will not be able to buy either on-exchange plans, where tax credits may be used, or off-exchange plans, which are not eligible for tax credits.

Vaughn said the structure of its 2017 footprint was designed to make sure there was at least one insurer in every part of the state. The 95 counties are divided among eight regions. In 2016, BCBST and UnitedHealthcare were the only two insurers to sell statewide.

BCBST's decision increases the number of counties in which people may choose from a single company to 73 counties — up from 57.

In the five where it remains, BCBST will offer four plans — one bronze, two silver and one gold — all on the statewide network S.

Maintaining that shoppers have options in all regions of the state, preferably more than one, has been a priority for the Tennessee Department of Commerce and Insurance. The agency allowed insurers to re-file for higher premium increases for 2017 after hearing that both Cigna and Humana thought initial requests to be too low.

In August, Insurance Commissioner Julie Mix McPeak characterized the exchange as being "very near collapse" because of the potential of losing insurers in some or all parts of the state. Aetna will sell off-exchange plans statewide for the first time although those will not be eligible for tax credits to offset the monthly premiums.

Spokespeople for Cigna and Humana declined to comment on filings with HHS until early October when final federal approval is expected.

"We intentionally chose to withdraw form regions where there were other insurance options available," said Vaughn. "In doing so we are trying to make sure Tennesseans have options for coverage in every region.”

Most Tennessean workers get insurance through employer-sponsored plans, according to a University of Memphis study, which estimates 82.5 percent employees in the state work for a company offering coverage. BCBST will still offer commercial, Medicare and Medicaid plans in all areas.

BCBST is not ruling out coming back into all markets — a decision it will assess every year.

The insurer would like to see the market stabilize, perhaps through tighter eligibility rules and additional younger members, as well as more certainty at the federal level where there is still clamor about changes and repeals.

"The ACA marketplace rules often change in the middle of the game. Beyond closing the gap between the medical costs we need to cover in our premiums, there are changes that could occur next year, mid-year that could put us in a loss position yet again," said Vaughn. "The prospect of future losses has us in a place where we believe we need to reduce our risk in hopes that this marketplace will stabilize at some point.”

Reach Holly Fletcher at 615-259-8287 or on Twitter @hollyfletcher.