The Affordable Care Act's coverage faces another challenge as Blue Cross and Blue Shield announced it will pull out of three markets in Tennessee and Nebraska in 2017.

In taking the dramatic steps it joins Aetna, Humana and United Healthcare, all of which are also looking to cut back involvement in some markets next year.

“We cannot take another hit,” Steve Martin, Blue Cross CEO, told the Omaha World-Herald. “We are very hopeful and will work with federal regulators with positive intent and try to be back in the marketplace next year. But if the markets are worse or don’t change, we can’t guarantee we’ll be back.”

BCBS has only about 20,000 policies for the individual exchange out of the 750,000 in the state. But those have led to $140 million worth of losses from 2014 to the present – and could have led to $250 million if the insurer had stayed in the marketplace through 2017. BCBS's coverage of employee groups, Medicare and Medicaid and other pre-ACA policies will remain unchanged. Higher benefit BCBS policies in the state obtained outside of the exchanges will also be dropped as they have been losing money, the company told the paper.

“We had to think long and hard about the effect on our company,” Blue Cross President Lew Trowbridge told the publication. “I mean, enough’s enough, and $140 million is a lot of money to us. We don’t see it ending, so we have to take corrective action now, as much as it pains us.”

One of the main issues raised by Martin is that the law lets people buy insurance just prior to needing high-cost treatments and then drop coverage.

“We believe the Affordable Care Act can be fixed, and we hope, post-presidential election, that whoever gets elected president and whoever is leading both sides of the aisle [in Congress] will come together and concentrate on making some fixes on this,” he stressed.

Research has demonstrated that the ACA works best in those states in which lawmakers expanded Medicaid – which Nebraska refused to do.

In Tennessee, the insurer is leaving the three largest exchanges – Nashville, Memphis and Knoxville. Calling the move “an extremely difficult but necessary decision," Roy Vaughn, chief communications officer of BCBS in Tennessee, told the Tennessean that, "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.”

Tennesseans will still be able to find coverage in those markets, Tatum Allsep, executive director of the Music Health Alliance, a nonprofit that helps musicians access health care, told the paper, stressing that, “the bottom line is everyone will still have access.”

The BCBS moves are just the latest made by big health care insurers lately. Aetna plans to pull the plug on much of its participation in the Affordable Care Act individual public exchanges for 2017.

Citing a second-quarter pretax loss of $200 million and total pretax losses of more than $430 million since January 2014 in its individual products, “we have decided to reduce our individual public exchange presence in 2017, which will limit our financial exposure moving forward,” Chairman and CEO Mark T. Bertolini said in a statement at the time, adding, “providing affordable, high-quality health care options to consumers is not possible without a balanced risk pool. Fifty-five percent of our individual on-exchange membership is new in 2016, and in the second quarter we saw individuals in need of high-cost care represent an even larger share of our on-exchange population.”

The jockeying for position by insurers is sure to continue. For example, even as it pulls out of some markets, BCBS plans to move into others. In Iowa, for instance, Wellmark Blue Cross and Blue Shield plans to offer individual plans on the exchanges in 40 of 99 counties, according to Forbes.