Activists say they're accepting nothing less than Medicare for all ABC News Correspondent David Wright examined Medicare for all on "This Week"

The healthcare proposal dubbed Medicare for all first gained traction as a campaign promise from Sen. Bernie Sanders in his 2016 presidential run.

The largest nurses union in the country, National Nurses United, actively campaigned for the policy then and has ramped up its grassroots push on the cause in recent months.

ABC News Correspondent David Wright examined the debate over transitioning to Medicare for all on ABC's "This Week" Sunday, speaking with experts and activists about the increase in support for the policy.

Building on the premise that access to health care is a right, Sanders' version of Medicare for all would replace most private insurance with a single-payer program based on the Medicare plan that is currently available to seniors and the disabled.

Matrese Chism, a registered nurse from Chicago who has been working on the issue at the grassroots level with the National Nurses United, sees the fight for universal health care as a civil rights issue.

"The United States is one of the largest, the greatest country in the world. And for us not to insure everyone, that is inhumane," she told Wright.

Many Democratic 2020 presidential candidates have supported the policy. Fellow Democratic candidates and Sens. Cory Booker, Elizabeth Warren, Kamala Harris and Elizabeth Warren regular reference the policy on the campaign trail and signed on as cosponsors for Sanders' Medicare-for-all bill in the Senate.

The momentum has made Medicare-for-all advocates hopeful.

"This is our moment, this is our time," Chism told Wright.

However, some health care experts have cautioned against the policy, which some estimates say could cost the federal government $32 trillion over 10 years.

"Making Medicare the litmus test on the Democratic side is a very bad idea," Ezekiel Emanuel, the Vice Provost for Global Initiatives at the University of Pennsylvania, told Wright. "We should be open to lots of ways of getting to universal coverage in the United States, but I also think it's a big political hill."

"It ought to be Medicare for none," Senate Majority Leader Mitch McConnell told Fox News in April. "You want to turn American into a socialist country, this is the first step."

For some Democratic candidates, the proposal is a bridge too far.

Former Vice President Joe Biden has proposed expanding Obamacare.

"Whether you're covered through your employer or on your own or not, you all should have a choice to be able to buy into a public option plan for Medicare," Biden said at his campaign kickoff in April.