The more relevant movement among Democrats is the revival of ideas to create a government-run insurance option to compete with private insurers on the ACA exchanges. That so-called “public option” was a top liberal priority during the initial debate over the ACA. Then, as now, proponents argued that a public insurance competitor—because it would not need to generate a profit—could offer a less expensive alternative and pressure private insurers to cut their premiums. Back in 2009, the House included a public option in the ACA version it passed, but the provision was dropped in the Senate amid opposition from several centrist Democrats led by Joe Lieberman, an independent from Connecticut who caucused with the party.

Two groups of Democratic senators have recently released bills to create a public option, both of which envision a considerably more aggressive role for government than even the House proposal did nine years ago.

One plan, from Senators Michael Bennet of Colorado and Tim Kaine of Virginia, would phase in the new public option. Americans buying coverage on the individual insurance market would be able to purchase it starting in 2020 in areas where few or no private insurance options are available. By 2023, the public option would be available for individuals nationwide. And in 2024, small businesses would be allowed to buy into the plan.

An alternative proposal, from Murphy and Oregon Senator Jeff Merkley, would move faster and further. It would make a public option immediately available not only to individuals, but also to employers of all sizes. And unlike the Bennet-Kaine plan, the Murphy-Merkley bill would also change how the ACA’s subsidies are distributed, by extending eligibility further into the middle class to help people buy coverage and by making those subsidies more generous.

Notably, both plans link the public option much more firmly to Medicare than the Democrats did in 2009. The plan the House approved back then encouraged hospitals and doctors that accepted Medicare to participate in the public option. But it also allowed them to opt out, and permitted them to charge participants in the new plan more than the rates Medicare pays.

Both of the new proposals would push providers much further, requiring those who participate in Medicare to accept patients choosing the new public option. That’s a huge lever, because few physicians can afford to renounce participation in Medicare. Both proposals would also require participating providers to accept Medicare reimbursement rates for the new patients (though each allows the government some wiggle room to raise rates if required to maintain a viable network). And, for good measure, each plan embraces the longtime liberal aim of empowering Medicare to use its buying power to negotiate for lower prescription-drug costs. Murphy told me his own bill offers a “public option on steroids” compared with the 2009 model. To a lesser degree, so does the Bennet-Kaine proposal.