For Sen. Lamar Alexander, two roads are diverging in a yellow wood.

The Tennessee Republican, who chairs the Senate, Health, Education, Labor and Pensions Committee, is facing a difficult quandary on health care that Democrats say could undermine a bipartisan reputation he has spent years cultivating and simultaneously determine the fate of the nation’s insurance system.

Alexander and Sen. Patty Murray of Washington, the top Democrat on the health panel, are making notable progress on a deal on short-term legislation intended to stabilize the individual market for 2018 and 2019 created by the 2010 health law.

Both have spent countless hours canvassing their caucus to determine what policy would be palatable for their colleagues, and have worked together for weeks on a compromise that could be agreeable to both parties.

Democrats praised the attempt by Alexander — who is by no means a fan of former-President Barack Obama’s signature domestic achievement — to try to find a bipartisan agreement on an extremely controversial issue.

And in a significant turn, Murray even agreed to including significant state flexibility in the package, a previous red-line for Democrats who were concerned that such a measure could undermine patient protections in the existing law.

But with the seemingly out-of-nowhere surge of support for the proposal from Sens. Bill Cassidy of Louisiana, Lindsey Graham of South Carolina, Ron Johnson of Wisconsin and Dean Heller of Nevada, that deal is on hold and the question of whether it will advance is an open one.

“This is clearly no longer about policy,” a Democratic aide said regarding the negotiations.

To complicate matters, Speaker Paul D. Ryan on Tuesday cautioned on Tuesday that any stabilization package that “props up Obamacare” will not be voted on by the House, Graham told reporters after the weekly Senate GOP policy lunch.

All of this puts Alexander, who famously left his post on Senate Republican leadership to try to cultivate more bipartisan work in the chamber, in a difficult spot.

He has long decried the law and has voted on numerous occasions to gut it. But Democrats said that voting for the measure from the Republican quartet that would drastically reshape the nation’s health care system would erode any trust Alexander was beginning to build with Murray and other members.

“I think it would hurt the effort that he’s undertaken,” Sen. Bob Casey, D-Pa., said. “I think it’ll be damaged.”

When asked whether Alexander’s ability to cut bipartisan deals in the future would be affected, Casey said “there’s no question it makes it harder.”

Republicans deny that Alexander’s decision would cause any ill will, and point to the number of deals — ranging from a major education overhaul to a large package of biomedical innovation bills — that he has made with Murray in the past few years.

And several GOP members cited Sen. Bernie Sanders’ recent single payer bill as a key source of hostility that helped spur movement on the health care repeal effort, a notion Democrats soundly reject.

Regardless of the hostility surrounding him, Alexander remains focused on his work across the aisle.

“What I’m trying to do — and what I’ve been trying to do with Sen. Murray and she’s been working in good faith as I have for a month — is to see if we can get a bipartisan consensus. And it’ll be have to be outside of the committee, because we can’t mark the bill up because part of it is in the Finance [Committee’s] jurisdiction,” Alexander said on Tuesday.

“Trying to get a bipartisan consensus in that environment this week is a lot harder than it was last week. I’m pretty good at getting bipartisan agreements, I’m not a magician,” he added.

But not all members of the Republican Conference appear on board with a bipartisan approach and there is an open question as to whether Senate Majority Leader Mitch McConnell, who has made it clear he supports the ongoing repeal attempt, would even put such a package on the chamber floor for a vote.

“There’s a little bit of irritation,” Senate Finance Chairman Orrin G. Hatch, R-Utah, said when asked about Alexander’s bipartisan bill.

The two panels have jockeyed in the past over jurisdiction on health-related matters, and it has come to the forefront in the most recent debate.

For his part, Alexander freely admits that support from Hatch would be necessary to move any bill forward. And he defends his effort with Murray as distinct from the Graham-Cassidy proposal

“It’s different than what I’ve been working on with Sen. Murray. That’s a short-term agreement — if we can get one — that would keep premiums from going up in 2018 and 19. Graham-Cassidy is long-term so I see them as separate ideas,” he told a group of reporters on Tuesday.

And while support grows for the Graham-Cassidy-Johnson-Heller bill, there are some within the Republican conference who want to keep the attention focused on the Alexander’s approach.

“The bipartisan approach has been proceeding very well,” Sen. Susan Collins of Main said. “My preference would be we continue along that line.”

Alexander insists there could be a vote on both measures.

But that seems unlikely given the damage that would be done to relationship between the two parties if a bill, which will not proceed through regular order and would be voted on without a full analysis from the Congressional Budget Office, were to pass.

And members of the minority party were blunt in their opinion of Alexander voting for the proposal.

“I’d be disappointed,” Sen. Angus King, an independent from Maine, said.

Alexander still has the support of one key Democrat. 

“I have a lot of faith in Senator Alexander’s belief in bipartisanship. I hope he won’t let those partisan pressures get him off course,” Senate Minority Leader Charles E. Schumer, D-N.Y., said. “A Howard Baker moment would be to go forward on this, and we know how much Senator Alexander admires Howard Baker.”

Lindsey McPherson contributed to this story.