WASHINGTON >> Sen. Bernie Sanders rode his impassioned liberal army of supporters through a tumultuous 2016, fighting to snatch the Democratic presidential nomination from Hillary Clinton. Now he’s disrupting the party anew, forcing Democrats to take sides over his plan to provide government-financed health care for all.

The Vermont independent’s proposal, which he plans to unveil Wednesday, is thrilling the party’s progressive base and attracting many potential 2020 presidential hopefuls eager to align those activists behind them. Yet Democratic leaders are stopping short of embracing it, and others are warning it’s a political and policy trap.

Meanwhile, the so-called single-payer bill has Republicans gleefully anticipating wielding it as a campaign weapon, particularly against the 10 Democrats defending Senate seats in states President Donald Trump won last year and where liberal voters are scarce.

“I’m not seeing any evidence single payer is attractive to the swing voters Democrats would need to win control of the House and Senate,” said Jim Hobart, a GOP political consultant. Using it against Democrats will be “a very inviting attack line,” he said.

Sanders evolved last year from a fringe senator to a major force commanding loyalty from progressive Democratic voters, activists and contributors. He could still seek the presidency in 2020, when he’d be 79. Clinton, in her new book, accuses him of inflicting lasting damage that hurt her chances of defeating Republican Donald Trump.

As described by aides, Sanders’ bill would essentially expand the Medicare health insurance program for the elderly to all Americans, covering virtually all medical needs except long-term nursing care. By this afternoon, it had been co-sponsored by at least 12 Democratic senators, including four other possible presidential contenders: Kamala Harris of California, Massachusetts’ Elizabeth Warren, New York’s Kirsten Gillibrand and Cory Booker of New Jersey.

Sanders denies that his proposal is causing rifts in his party.

“You mean because the people in this country want to move toward a Medicare-for-all system, that is divisive?” he said in an interview today, citing polls showing growing support. “I think in a democracy, we should be doing what the American people want.”

With Trump in the White House and Republicans controlling Congress, the bill has no chance of becoming law soon. But for many Democrats, it unfurls an irresistible mix of liberal policy goals: Universal health care and a simpler medical system that would be less expensive than today’s for many, likely financed with taxes exempting the poorest Americans while heavily hitting the rich and corporations.

Sanders’ plan is “a different value system, one where we all take care of each other and where health care is a right,” Robert Weissman, president of Public Citizen, told reporters today. He added, “This is no longer going to be a fringe position.”

Sanders has released no price tag. The version he advanced during his presidential campaign would have cost a huge $1.4 trillion a year.

A similar House bill by Rep. John Conyers, D-Mich., has 117 co-sponsors, more than half that chamber’s Democrats, underscoring the concept’s growing acceptance in Democratic circles. Yet, others are keeping their distance.

Underscoring the unease, House Minority Leader Nancy Pelosi, of California, a long-time backer of the single-payer idea, declined to endorse Sanders’ measure today. She told reporters her focus is defending President Barack Obama’s health care law from the all-but-dead Republican attempt to repeal it. Senate Minority Leader Chuck Schumer, D-N.Y., noted that Democrats have introduced several bills on expanding coverage and said, “We’re looking at all of them.”

While Sen. Tammy Baldwin of the swing state Wisconsin is backing Sanders’ bill, Democrats facing tough re-election campaigns in GOP-tilting states are being more cautious. Sens. Jon Tester of Montana and Heidi Heitkamp of North Dakota say they prefer to improve the existing health care law, not scrap it.

Several others are offering alternatives that will let Democrats vote “yes” to expand government-provided health care without the all-in move Sanders wants.

Sen. Sherrod Brown, D-Ohio, a potential presidential hopeful, said he’s pushing another bill with Sen. Debbie Stabenow, D-Mich., to let people over age 55 buy into Medicare, 10 years younger than now. Sen. Chris Murphy, D-Conn., another 2020 presidential possibility, has his own Medicare buy-in plan.

Adam Green, co-founder of the Progressive Change Campaign Committee, which works for liberal candidates, said he supports multiple efforts to move toward universal coverage and warned that candidates who don’t back such efforts would be “forfeiting a degree of support.”

Still other Democrats see Sander’s proposal as a nightmare for the party that would make its candidates easy targets for the GOP.

Republicans are poised to paint it as a mammoth tax increase that puts government in control of health care, which the GOP has used as a potent attack line in the past. It would wrest employer-provided health care away from the roughly half of Americans who get coverage that way, a disruption for about 150 million people.

“It’s laughable,” Sen. Bill Cassidy, R-La., said of Sanders’ bill, saying it would appeal to voters “who don’t understand the expense of it.” Sen. Jerry Moran, R-Kan., said the measure was aimed at “a section of the Democratic base that needs to be appealed to.”

And as the GOP’s failed effort to repeal Obama’s 2010 law has demonstrated, opponents can latch onto a plan’s details to shove its popularity downward. A June poll by the nonpartisan Kaiser Family Foundation found that while a slight majority favor single payer, support fell significantly when people were told it would mean government control, higher taxes and replacing Obama’s 2010 statute.

“There’s a Sanders grassroots that aims to pressure Democrats to support this and make it a litmus test, which would be a disaster,” said Jim Kessler, a senior vice president for Third Way, a Democratic centrist group.