Joseph Swedish, chief executive officer of Anthem. T.J. Kirkpatrick | Bloomberg | Getty Images

A new analyst report says there is reason to believe that major Obamacare insurer Anthem "is leaning toward exiting a high percentage" of the insurance regions where it currently sells individual health plans. If that happens, millions of Obamacare customers and potential customers would be left in 2018 with even fewer choices of insurers than they have now. The report on Thursday from Jefferies comes almost two months after Anthem CEO Joseph Swedish warned the insurer, which sells plans under the Blue Cross Blue Shield might decide within months "whether or not we surgically extract ourselves from certain rating regions, or even on a larger scale, depending on the stability of the marketplace." In recent conversations with Jeffreries analysts, Anthem management referred to the statements about "surgical reductions, but currently seems to be leaning toward broader extraction," the report said.

News of the Jefferies' analysis first was reported by Bloomberg. Anthem currently insures more than 800,000 individual plan customers in 144 rating regions in 14 states. Other major insurers, including Aetna, UnitedHealthcare, Cigna and Humana, have already scaled back their footprints in the Obamacare markets. But Anthem's exit would potentially have a bigger impact. Earlier this month, an analysis by Axios.com said, "An Anthem exit would cause arguably the most disruption nationwide." "Roughly 255,000 people across Colorado, Kentucky, Missouri and Ohio would have no Obamacare insurers for 2018, and 560,000 people in eight states would have just one insurer," the analysis by Axios.com said. Anthem's management has indicated that it would like regulatory changes that could lower the financial risk it runs in insuring Obamacare customers. The Jefferies report said that management told the analysts that "regulatory advocacy needs to progress significantly in the next 'month or so.' "

"Improvements such as eligibility verification, more rigid special enrollment periods, shortening of premium grace periods are steps in the right direction, but not enough," the Jefferies analysts wrote of Anthem's view. Another factor that would play into Anthem's decision on whether, and to what extent, to pull out of Obamacare markets is the level of health claims that its current pool of customers will end up having this year. Management told Jefferies that it normally takes up to six months of claims "to get a sense of risk profile on its new enrollees (so, mid-year)."

Anthem's management also expects that state insurance departments will tend to approve substantially higher premium rates for 2018 plans, as they did for plans that went into effect in January of this year, "in efforts to sustain individual markets." Asked about the Jefferies report, Anthem told CNBC that the company "has served consumers in the individual health insurance market for over seven decades." "Since the launch of the ACA in 2014, we have been in continuous dialogue with previous and current administrations and Congress to emphasize the importance of regulatory and statutory changes in order to ensure sustainability and affordability of the Individual market for consumers," Anthem said. "We continue to actively pursue policy changes that will help with market stabilization and achieve the common goal of making quality health care more affordable and accessible for all." Robert Laszewski, a health insurance analyst, in a blog post on the Jefferies report, wrote, "Will Anthem, part of the Blue Cross Blue Shield exchange market backbone left in most of the states, really exit? Or, is this just a negotiating ploy just as the Trump administration is about to make key decisions regarding the Obamacare exchange market for 2018?" "I have my doubts that Anthem will end up exiting the Obamacare exchanges," wrote Laszewski, president of Health Policy and Strategy Associates. "While Anthem is a publicly traded company, its legacy Blue Cross plans in the 14 states in which it participates have a long tradition of being a community partner." Watch: Lingering Obamacare court cases trouble insurers