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 Tuesday 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 Tuesday, 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 Tuesday. 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 Tuesday. 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.”