With the Republican effort to repeal and replace Obamacare currently dead, Senate Majority Leader Mitch McConnell, R-Ky. vowed to revive the 2015 bill that repealed much of Obamacare's taxes and spending (while leaving regulations intact), and then deal with the thorny negotiations about replacement after. Back in 2015, the partial repeal bill passed the Senate with a 52-vote majority.

Though there has been some turnover in the Senate since that December 2015 vote, many of the centrists who have been the most reluctant to repeal Obamacare — Sens. Shelley Moore Capito, R-W.V., Lisa Murkowski R-Alaska., Dean Heller, R-Nev., Bill Cassidy, R-La., and Rob Portman, R-Ohio — voted for the repeal bill. If they oppose it this time, they'll have to beat back charges that they cynically voted for repeal two years ago when they knew former President Barack Obama would veto it, but reversed themselves when it was no longer symbolic, because President Trump will sign it into law. Susan Collins, R-Maine, voted no in 2015.

The bottom line: If McConnell is somehow able to hold all of the senators who voted for repeal in 2015, it would probably pass, because the new senators are from very conservative states.

Below is a full list of how those in the current Senate voted in 2015, and how the composition of the Senate has changed since then.

VOTED YES

Lamar Alexander, R-Tenn.

John Barrasso, R-Wyo.

Roy Blunt, R-Mo.

John Boozman, R-Ark.

Richard Burr, R-N.C.

Shelley Moore Capito, R-W.V.

Bill Cassidy, R-La.

Thad Cochran, R-Miss.

Bob Corker, R-Tenn.

John Cornyn, R-Tex.

Tom Cotton, R-Ark.

Mike Crapo, R-Idaho

Ted Cruz, R-Tex.

Steve Daines, R-Mont.

Mike Enzi, R-Wyo.

Joni Ernst, R-Iowa

Deb Fischer, R-Neb.

Jeff Flake, R-Ariz

Cory Gardner, R-Colo.

Lindsey Graham, R-S.C.

Chuck Grassley, R-Iowa

Orrin Hatch, R-Utah

Dean Heller, R-Nev.

John Hoeven, N.D.

James Inhofe, R-Okla.

Johnny Isakson, R-Ga.

Ron Johnson, R-Wis.

James Lankford, R-Okla.

Mike Lee, R-Utah

John McCain, R-Ariz.

Mitch McConnell, R-Ky.

Jerry Moran, R-Kan.

Lisa Murkowski R-Alaska.

Rand Paul, R-Ky.

David Perdue, R-Ga.

Rob Portman, R-Ohio

James Risch, R-Idaho

Pat Roberts, R-Kan.

Mike Rounds, R-S.D.

Marco Rubio, R-Fla.

Ben Sasse, R-Neb.

Tim Scott, R-S.C.

Richard Shelby, R-Ala.

Dan Sullivan, R-Alaska

John Thune, R-S.D.

Tom Tillis, R-N.C.

Pat Toomey, R-Pa.

Roger Wicker, R-Miss.

VOTED NO

Susan Collins, R-Maine

NO LONGER IN OFFICE

Kelly Ayotte, R-N.H. (lost in 2016)

Dan Coats, R-Ind. (became Director of National Intelligence, replaced by Todd Young)

Jeff Sessions, R-Ala. (became Attorney General, replaced by Luther Strange)

David Vitter, R-La. (did not seek reelection, replaced by John Kennedy)

Mark Kirk, R-Ill. (lost in 2016, voted no initially)

NOW IN OFFICE

John Kennedy, R-La.

Luther Strange, R-Ala.

Todd Young, R-Ind.