A quarter of Democratic Caucus members in the U.S. Senate have now signed on as co-sponsors of Sen. Bernie Sanders' (I-Vt.) Medicare for All bill, which he plans to introduce Wednesday, signaling a shift among party lawmakers, who may be swayed by recent polling that has indicated a majority of Americans and more than two-thirds of Democrats favor a single-payer national healthcare system.

As of this writing on Tuesday afternoon, the 12 co-sponsors are:

Sens. Tammy Baldwin (D-Wis.)

Richard Blumenthal (D-Conn.)

Cory Booker (D-N.J.)

Kirsten Gillibrand (D-N.Y.)

Kamala Harris (D-Calif.)

Mazie Hirono (D-Hawaii)

Ed Markey (D-Mass.)

Jeff Merkley (D-Ore.)

Brian Schatz (D-Hawaii)

Elizabeth Warren (D-Mass.)

Sheldon Whitehouse (D-R.I.)

Tom Udall (D-N.M.)

Udall, the most recent addition, announced his co-sponsorship with a statement posted to Twitter:

Health care is a human right. Every American should be able to see a doctor when they’re sick. That’s why I support #MedicareForAll. pic.twitter.com/LcfviYwTYD — Tom Udall (@SenatorTomUdall) September 12, 2017

Last weekend, Sen. Patrick Leahy said he is "likely to support" the bill, but he has not yet come out as a co-sponsor.

As senators lined up to pledge their support on Monday and Tuesday, it became clear that since Sanders made single payer central to his 2016 presidential campaign, the political needle has indeed shifted.

Sharing a Politico piece titled "Democratic foes of Trump flock to single-payer ahead of 2020"—which references predictions that any potential 2020 challenger to President Donald Trump will need to support single payer to win over voters—Students for National Health Program enthusiastically welcomed the surge of endorsements while journalist and activist Shaun King called the shift "a groundbreaking development."

That a momentous group of US Senators is coming together to stand for #MedicareForAll is HUGE news. It's a groundbreaking development. — Shaun King (@ShaunKing) September 12, 2017

In a Washington Post news analysis, entitled "The dam is breaking on Democrats' support for single player," Aaron Blake noted how during last year's Democratic primary season, "Hillary Clinton dismissed single-payer as 'a theoretical debate about some better idea that will never, ever come to pass.' Fast-forward a year, and it's leading Democratic presidential hopefuls like Clinton that are spearheading this."

SCROLL TO CONTINUE WITH CONTENT Never Miss a Beat. Get our best delivered to your inbox.







Supporters of Sanders and a Medicare for All healthcare system have deemed the coming legislation a "litmus test" for Democrats. Though Sanders, in an August interview with the Post, disagreed that the bill would serve as litmus test, he was quick to point out the growing support for a single-payer system, and added: "as more and more Americans come on board, it will become politically possible."

The litmus test theory could be tested before 2020. Baldwin is up for re-election in Wisconsin in 2018, which makes her announcement that she's co-sponsoring the bill a "big deal," said MoveOn.org Washington Director Ben Wikler.

Seriously a big deal. @tammybaldwin co-sponsoring Medicare For All shows the way for Ds up for reelection in states Trump won: *stand tall.* — Ben Wikler (@benwikler) September 12, 2017

Even Sen. Joe Manchin (D-W.V.), whom Bloomberg calls "the Senate's most conservative Democrat," told the outlet on Tuesday that he is open to considering single payer. Manchin, like Baldwin, is up for re-election next year.

Despite the widespread support from the public, and now a substantial number of Sanders' fellow senators, some lawmakers have said they first want to see the bill, while others have overtly declined to support it. Based on what they've told Capitol Hill reporters this week, Sens. Chris Van Hollen (D-Md.), Ron Wyden (D-Ohio), Bob Casey Jr. (D-Penn.), and Chuck Schumer (D-N.Y.) remain undecided.

Sen. Tim Kaine (D-Va.) told Vox's Jeff Stein that he prefers a healthcare program that allows people to pick between a government-run program and private insurers, and Sen. Dianne Feinstein, claiming "the cost of single payer is enormous," said she too supports a public option instead of Medicare for All.

.@timkaine pretty much rules out getting on single-payer bill, tells me and @PeterSullivan4 he prefers more choice in marketplace — Jeff Stein (@JStein_Vox) September 11, 2017

Sen. Sherrod Brown (D-Ohio)—typically known for his progressive stances—said he's focusing on his own healthcare bill and will not co-sponsor Sanders' bill. However, Brown also said in a statement to Politico that he's "always been supportive of Medicare for All," implying he may not oppose the legislation once it's introduced.

Sen. Debbie Stabenow (D-Mich.), who's sponsoring the "Medicare at 55 Act" with Brown, also said she wants to focus on their bill, while Sens. Claire McCaskill (D-Mo.) and Jon Tester (D-Mont.) both told The Hill's Peter Sullivan on Tuesday that they will not support Sanders' proposal.

Mccaskill with the strongest no on sanders bill I've heard today. Said Medicare costs need to be addressed first — Peter Sullivan (@PeterSullivan4) September 12, 2017