Sens. Chris Murphy (D-CT) and Jeff Merkley (D-OR) are out Wednesday with a new Medicare buy-in proposal, one that allows both individuals and large employers to purchase coverage through the public program that covers elderly Americans.

We’ll get to the substance of the bill in a moment. But first, I want to highlight the fact that this bill enters an increasingly crowded field of liberal health care proposals, all of which want to go beyond the Affordable Care Act and increase the government’s role in providing health care services.

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By my count, we currently have five major proposals on the table, each envisioning different futures for the American health care system:

A Medicare-for-all bill from Sen. Bernie Sanders

A Medicare buy-in bill from Sens. Tim Kaine and Michael Bennet

A Medicaid buy-in bill from Sen. Brian Schatz

A Medicare “extra”-for-all proposal from the Center for American Progress, an influential liberal think tank that has strong ties to Clinton-land

This new Medicare buy-in bill from Sens. Murphy and Merkley

It’s notable to me that Democrats seem really keen on having another health care debate. They’re preparing for it by putting all these different options on the table, to sort through where a consensus might exist.

That Democrats would continue pursuing health policy as a key priority isn’t a given. There are plenty of different priorities they could pursue if they regain a congressional majority and control of the White House. Immigration, infrastructure, climate change ... the list of potential policies goes on and on. The last health care debate was incredibly bruising, with the Affordable Care Act remaining divisive eight years after passage — never attaining the popularity that some Democrats expected.

But when I had a chance to discuss this with Sens. Murphy and Merkley Tuesday, they made the case that health care will definitely be a top item in the party’s agenda — that Democrats will return to the issue that defined the early 2010s.

“There is no question we’ll have to act,” says Murphy. “It’s the No. 1 issue in America. The polls are clear.”

Merkley added that even though the Affordable Care Act has expanded coverage to some, many still “worry about additional costs, that their co-pays will be increased or individual provider leave the network.”

“Generally people who are in Medicare have peace of mind,” he continued. “This is why it’s such a widely regarded, highly appreciated program. ... This is why we’ll have to absolutely engage in health care.”

Now, let’s get to the Murphy-Merkley plan itself

The Choose Medicare Act would allow individuals and large businesses to buy coverage through the Medicare plan. This would go a bit beyond the Kaine-Bennet version of a Medicare buy-in, which limits that choice to individuals. The Murphy-Merkley plan would allow, for example, a company like Vox Media to purchase Medicare for its employees rather than buy coverage from the private health plan we currently use.

The idea at the heart of this (and any) Medicare buy-in plan is that individuals and companies would benefit from the public program’s strong bargaining power. It tends to set lower rates than private insurance plans. Doctors still accept those rates because Medicare covers a massive amount of people — about 45 million Americans or 14 percent of the population. Medicare would gain even more bargaining power, the theory goes, as more and more people join the program.

The Choose Medicare Act envisions that individuals and companies would cover their costs for buying into Medicare, meaning actuaries would need to determine what those premiums would look like. There is some reason to expect these premiums would be lower than premiums for private insurance, because Medicare typically pays lower prices. But the senators haven’t actually run the numbers on this or begun discussions with the Congressional Budget Office, so we don’t really know.

Obamacare enrollees who receive subsidies to purchase health insurance would be able to put those subsidies towards buying into Medicare, just as they do now with private plans.

Speaking of those subsidies, the most expensive element of this plan arguably has nothing to do with Medicare at all. Murphy and Merkley envision using their bill to really bump up the Obamacare subsidies, extending them to cover all Americans who earn less than 600 percent of the federal poverty line (right now, they stop at 400 percent). They would also change how the subsidies are calculated, to give people enough money to buy one of the more generous “gold” plans on the marketplace (right now, the subsidies are tethered to the less generous “silver” plans).

Merkley and Murphy aren’t quite in the same place when it comes to what Democrats should do next on health care. Murphy, for example, hasn’t endorsed Sen. Sanders Medicare-for-all plan but Merkley has.

“One of the reasons that we wanted to work together is that we’re in different places,” Murphy says. He argues that their bill is the best path forward because it allows a way to “test the idea that Americans will want a Medicare product.”

I mostly take the Murphy-Merkley bill as a sign that Democrats are eager to have another health care debate, that they see problems that the Affordable Care Act didn’t fix — and, rather than being battle-scarred from the last Obamacare debate, seem eager to take another swing at a contentious issue.

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