A new wrinkle in the health care negotiations in the Senate – in return for a climb-down on the public option, some Democrats are seeking different measures, like a buy-in to Medicare for ages under 65.

The proposal would lower the age of eligibility for Medicare from 65 to 55, though an age limit of 60 has also been suggested. Crucial details — such as the timing of the implementation of such a reform — were not provided due to the sensitivity and ongoing nature of the deliberations. A high-ranking Democratic source off the Hill confirmed that such discussions are taking place.

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, one of the sources added. Senate Democrats held discussions this past weekend about replacing Senate Majority Leader Harry Reid’s version of a public plan with one that would be non-profit-based. The alternative proposal would be offered in state exchanges, run by private insurers but monitored by the Office of Personnel Management.

“The Office Personal Management proposal that has been out there for the past couple days is one of the leading ideas to represent the public option in a modified bill. But there are a series of things that progressives are negotiating in exchange for dropping the [public option] opt-out,” said the source.

There’s a lot of interest here. First, it must be made clear that, just because something’s being talked about doesn’t mean it will happen. The negotiations appear to be returning to the overall usefulness of the bill rather than what compromised compromise on the public option ConservaDems would accept, but I have a hard time believing they would accept an expansion of programs like Medicare or Medicaid (taking it to 150% of the poverty level, in line with the House bill, has also reportedly been discussed) when they’ve spent weeks warning against government-run health care. If Blanche Lincoln or Joe Lieberman don’t want to see a march to single payer, why would they allow for buy-ins to Medicare, the single easiest way to get to single payer?

The one reason that ConservaDems may accept it is that these moves actually save money. It’s cheaper to expand Medicaid than to pay the subsidies between 133-150% for people to purchase insurance. It’s cheaper to allow people to buy into Medicare than what you would pay in subsidies. That’s mainly because of the rate schedule and the lower price for Medicare. What’s more, Republicans in particular have spent a week falling all over each other trying to “save Medicare,” and watching them caution against buy-in would be most amusing to watch.

The money saved from these public coverage expansions could be plowed into higher subsidies, which are needed under the Senate bill. But that’s all anyone age 27-55 would get out of this – they would be left basically with a forced mandate to buy private insurance.

Where does this all leave the public option? In a van down by the river is where. The idea here is to basically offer something like Medicare buy-in or Medicaid expansion or bigger subsidies or a tightening of the medical loss ratio for insurers (what percentage of premiums must go to medical care) in exchange for basically dropping or triggering the public option. Will that be acceptable? Private insurance companies would still predominate, and Americans would still be forced under this bill to send them premium money for coverage that may or may not be sufficient. Most importantly, the architecture of a public option, as a benchmark which could be improved upon to change incentives for insurers, could be gone.

By contrast, there’s an argument that Medicare buy-ins could be pushed downward, Medicaid and age limits for staying as a dependent on plans pushed upward, until they met in the middle, and basically everyone was covered. As this argument goes, the architecture still exists, just in a different form.

I’m not sure I agree. But one thing is clear – nobody has agreed to anything. There’s no use debating the wisdom of this measure until someone like Joe Lieberman or Olympia Snowe comes out and says they’d vote for a bill with this in it. On the opt-out, we saw all this activist attention paid to it, without any ConservaDem agreeing to it, making it useless.

I’m less interested in chasing this trial balloon until some conservative validator goes ahead and endorses it.