Medicare has long been one of the most popular programs administered by the federal government.

It is so popular that congressional Republicans – whose party once led the opposition to creating Medicare and has long sought to limit and undermine it – have this year been arguing that they oppose health-care reform because it might harm the Medicare program.

That is one of the reasons why the current health-care reform push should have been framed as a “Medicare for All” initiative – a theory advanced for many years not just by advocates for a single-payer system but by more moderate reformers such as former Vermont Governor Howard Dean.

During the early stages of the current debate, a number of House Democrats have talked about lowering the eligibility age for Medicare – not just to expand access to health care but as a smart response to concerns about unemployment and economic turbulence.

As economist James K. Galbraith has noted, “Increasing benefits is a simple, direct, progressive, and highly efficient way to prevent poverty and sustain purchasing power for this vulnerable population. I would also argue for lowering the age of eligibility for Medicare to (say) fifty-five, to permit workers to retire earlier and to free firms from the burden of managing health plans for older workers.

Now, as the Senate wrestles with the question of how to craft a health-care reform measure that will win the support needed to avert GOP filibuster threats and to pass a credible measure, the idea of dropping the Medicare eligibility age from 65 to 55 has resurfaced as a prospect.

Under the proposal, which is being weighed by Senator Jay Rockefeller, D-West Virginia, and several other senators who are in the thick of the latest negotiations, Americans as young as 55 who lack affordable coverage could buy plans under Medicare.

“There has been a pretty reasonable reaction to it,” says Rockefeller, one of the Senate’s most ardent reformers. “We’re negotiating,” adds the chair of the Health Care Subcommittee on the Senate’s powerful Finance Committee.

The Medicare eligibility issue is one of many that are suddenly in play as key Democratic senators wrestle with the question of whether a final bill that lacks a public option might still have appeal to real reformers.

“Lowering the floor for Medicare is one of several ideas being discussed as a way to pacify progressives upset over the potential elimination of a public option for insurance coverage,” according to media reports, which suggest that details regarding the move (the precise eligibility age, the timetable for making the change, funding mechanisms) are still in play as part of ongoing deliberations.

The plan seems to be picking up traction in the Senate. But most senators, even fans of the idea, are waiting for cost estimates from congressional budget analysts before embracing it.

Several progressive members of the House and Senate have confirmed to this reporter that lowering the Medicare eligibility age would have serious appeal in their caucuses. But there is some disagreement about how serious the prospect may be, especially considering the determination of some conservative and moderate members of the Democratic caucus in the Senate to control entitlement costs.

What should real reformers make of the notion of lowering the eligibility age?

By any measure, they ought to be excited.

Expanding a strong public program to cover and care for more Americans is a smart way to achieve a needed goal.

It is, as well, a savvy intervention in the current health-care and economic debates that has long-term repercussions. Once the eligibility age is lowered, it won’t go up. Once the precedent of lowering the age as a means of expanding access has been established, it can be revisited to further expand access.

None of this is an argument for compromise on the public option, or for any other compromises.

Rather, it is an argument that real reformers should recognize that talk about lowering the eligibility age for Medicare is incredibly significant – and genuinely hopeful – news for those of us why seek to repair a broken health-care system.