Blue Cross plans could lose 60 percent of their revenues from the individual market if people over 50 are shifted to Medicare, said Kris Haltmeyer, an executive with the Blue Cross Blue Shield Association, citing an analysis the company conducted. He said it might not make sense for plans to stay in the A.C.A. markets.
Siphoning off such a large group of customers could also lead to a 10 percent increase in premiums for the remaining pool of insured people, according to the Blue Cross analysis. More younger people with expensive medical conditions have enrolled than insurers expected, and insurers would have to increase premiums to cover their costs, Mr. Haltmeyer said.
Tricia Neuman, a senior vice president at the Kaiser Family Foundation, which studies insurance markets, said a government buy-in that attracted older Americans could indeed raise premiums for those who remained in the A.C.A. markets, especially if those consumers had high medical costs.
But some experts countered that prognosis, predicting that premiums could go down if older Americans, whose health care costs are generally expensive, moved into a Medicare-like program.
“The insurance companies are wrong about opposing the public option,” Ms. Shalala said.
Dr. David Blumenthal, the president of the Commonwealth Fund, a foundation that funds health care research, said a government plan that attracted people with expensive conditions could prove costly.
“You might, as a taxpayer, become concerned that they would be more like high-risk pools,” he said.
Jonathan Gruber, an M.I.T. economist who advised the Obama administration during the development of the A.C.A., likes Mr. Biden’s plan and argues there is a way to design a public option that does not shut out the private insurers.
“It’s all about threading the needle of making a public option that helps the failing system and not making the doctors and insurers go to the mat,” he said.