Health care reform teetered on the brink of collapse Thursday as House and Senate leaders struggled to coalesce around a strategy to rescue the plan, in the face of growing pessimism among lawmakers that the president’s top priority can survive.

The legislative landscape was filled with obstacles: House Democrats won’t pass the Senate bill. Senate Democrats don’t want to start from scratch just to appease the House. And the White House still isn’t telling Congress how to fix the problem.

House Speaker Nancy Pelosi (D-Calif.) and Senate Majority Leader Harry Reid (D-Nev.) both tried to put a good face on the obvious chaos on Thursday, promising to press on.

“We have to get a bill passed,” Pelosi told reporters. “We know that.”

Senate Finance Committee Chairman Max Baucus (D-Mont.) said, “No way is it dead, because it’s so important for the country. And we will find a way to pass [it].”

But for the first time in the yearlong push, Democratic aides — and even some members — finally acknowledged privately that the fear of failure was real. And Congress recessed for the weekend without an obvious path forward as rank-and-file Democrats started splintering in different directions.

Democrats struggled all year to maintain a coalition in support of health care reform without any GOP votes. Republican Scott Brown’s improbable win in Massachusetts on Tuesday now looks like it has the potential to end that almost-impossible balancing act.

This post-Massachusetts confusion raises the stakes for President Barack Obama’s first official State of the Union address next week, which some now believe must be a last-ditch effort to get health care finished.

On Thursday, Sen. Chuck Schumer (D-N.Y.), a fierce proponent of health reform, said it wasn’t clear how the Senate should press ahead.

“Obviously, you cannot just proceed as if nothing happened, because something very significant happened,” Schumer said, referring to Brown’s victory. “There is a strong view in both caucuses that we want to do some good things in health care, and the question is how? How much and how quickly?”

Pelosi took one option off the table Thursday when she told reporters that she doesn’t have the votes to pass the Senate bill unless it undergoes major changes. The White House had hoped to avoid a protracted health care fight by getting the House to adopt the Senate bill, despite deep misgivings among House Democrats.

That leaves two main options for moving forward:

The first would be to pass a scaled-back health care bill, but it remains to be seen what that would look like. Liberal groups have already assailed the idea for falling short of the president’s initial goal of near-universal coverage. And the second idea is for the House to pass a so-called corrections bill that would make changes to the Senate legislation but would require the Senate to pass the second bill as well.