Sen. Bernie Sanders (I-Vt.) unveiled Wednesday a new version of his plan to give everybody government-run health insurance , potentially opening a new chapter in the ongoing debate over how to make health care in the U.S. more affordable and available.

The plan calls for an overhaul of American health insurance with a souped-up, more generous version of Medicare replacing nearly all private health insurance and government exerting far more control over the cost of medical care. It would arguably be the most ambitious social welfare initiative in U.S. history, but Sanders told HuffPost in an interview Tuesday that he believes America is ready for it.

The American people are catching on to where the Republicans are coming from, they see the limitations of the Affordable Care Act and theyre looking at the alternatives, Sanders said. And this is a rational alternative.

Sanders has been waging a frequently lonely crusade for this kind of universal health care since the early 1990s, when he first came to Congress . In 2013, when he introduced a previous iteration of the bill, he had no support from his colleagues. But in a clear sign of the ideas increasing popularity, as well as Sanders influence within progressive politics, 16 Democratic senators are co-sponsoring the bill.

Thats more than one-third of the Senate Democratic caucus. Staffers told HuffPost they had expected less than half as many senators to sign on, and they attributed the broad appeal to a five-month drafting period in which they solicited input from the offices of 19 senators, including several who they knew never had any intention of getting behind the bill.

That roster of co-sponsors includes a whos-who list of potential Democratic presidential candidates for 2020, including Cory Booker of New Jersey, Kirsten Gillibrand of New York, Kamala Harris of California and Elizabeth Warren of Massachusetts. Also backing the bill are Patrick Leahy of Vermont, Sheldon Whitehouse of Rhode Island, Al Franken of Minnesota, Jeff Merkley of Oregon, Ed Markey of Massachusetts, Martin Heinrich and Tom Udall of New Mexico, Brian Schatz and Mazie Hirono of Hawaii, Richard Blumenthal of Connecticut, Jeanne Shaheen of New Hampshire and Tammy Baldwin of Wisconsin.

Among the co-sponsors, Baldwin is notably up for re-election in 2018 in a state President Donald Trump won narrowly in November. But Sen. Sherrod Brown , a reliably progressive Democrat up for re-election in Ohio, where Trump won by 8 percentage points , has thus far declined to get behind the bill.

For evidence that Americans increasingly see single payer as the solution to the ACAs flaws, Sanders suggested people look no further than the unexpected and rapid success he had recruiting co-sponsors for his bill. As if to dramatize the phenomenon, an aide interrupted the beginning of his interview with HuffPost to put him on the phone with Franken, who had called to inform Sanders he would be joining as well.

Even with the strong show of support from Democrats, the likelihood of the Sanders proposal passing in the near future would seem to be vanishingly remote, in no small part because the Republicans who control Congress generally dont believe in universal coverage and are more interested in repealing existing government health programs than creating new ones.

But Sanders thinks support for the idea is growing, making future enactment possible. Youre seeing it in polling, youre seeing it in town meetings, youre seeing the American people waking up and demanding that we end this dysfunctional system and we join the rest of the industrialized world.