Then after budget cuts imposed in 1997 drove many private plans to drop out of the program, Congress steadily raised their payments. Today Medicare pays the private plans, on average, 14 percent more than the same services would cost in traditional Medicare.

The bill being considered by the Senate Finance Committee is projected to cut the subsidies to Medicare Advantage companies by more than $100 billion over 10 years. Although Republican rhetoric has triggered fears that Medicare Advantage enrollees might lose their coverage entirely if private plans drop out of the system, the real effect of the bill would likely be modest on average.

The value of an enrollee’s added benefits would shrink by more than half from current levels but would not disappear; they would still be worth about $500 a year in 2019.

Douglas Elmendorf, the director of the Congressional Budget Office, told the committee that, under the bill as proposed by the committee chairman, he expected that almost all Medicare Advantage plans would continue to operate and almost all of their current enrollees would stay enrolled. Total enrollment in Medicare Advantage would creep up by 200,000 over the next decade  that is, about 2.7 million fewer new enrollees than expected under current trends, a real chance for savings.

What the Republicans aren’t saying  and what the Democrats clearly aren’t saying enough  is that in important ways, coverage for a vast majority of Medicare recipients, those in traditional Medicare, should actually improve under health care reform.

The House legislation, the only bills in near-final form, would reduce and ultimately eliminate a gap  the so-called doughnut hole  in Medicare drug coverage that currently forces more than three million beneficiaries to pay for drugs entirely out of their own pockets once they hit specified spending levels. That would also benefit many other beneficiaries who pay high premiums for coverage in the gap that they never end up using.

The House bills would also waive deductibles and co-insurance for preventive care that can head off serious illness, expand eligibility for programs that assist low-income beneficiaries and provide incentives for doctors and hospitals to coordinate care, improve quality, and lower costs. All that should benefit many if not most Medicare beneficiaries. And delivery system reforms should benefit the private plans as well.