Updated at 9:30 p.m. with results from a vote on a measure by Texas Sen. Ted Cruz.

WASHINGTON — After months of raucous negotiations and embarrassing setbacks, GOP leaders narrowly cleared a critical hurdle on Tuesday in their quest to dismantle the Affordable Care Act.

But just hours later, the party faced an expected first defeat, as a vote to advance a version of the GOP's Better Care Reconciliation Act that included a proposal by Texas Sen. Ted Cruz failed to move forward.

GOP leaders downplayed that setback, still riding high from gaining the support of 50 Republicans to even begin debate on a health care replacement measure, a goal that has eluded Republican lawmakers in recent months as they navigated health care disagreements.

Two senators -- Susan Collins, of Maine, and Lisa Murkowski, of Alaska, voted against the motion to proceed. Vice President Mike Pence broke the tie, starting the clock on hours of debate over still-evolving health care legislation. The process will include a flurry of amendments as conservative and moderates seek to shape the bill in their favor in coming days.

"Let the voting take us where it will," Senate Majority Leader Mitch McConnell said ahead of the vote.

Democrats, meanwhile, will pitch a last ditch — but likely unsuccessful — effort to salvage President Barack Obama’s landmark health care law.

The final bill — what it will look like, how it will affect health care for millions of Americans, and whether it can win the support of a fractious GOP party — is still unknown, a point acknowledged by Cruz on Tuesday.

"At this point, it's not clear what the final product will be of all of these amendments," he said. "But I think the key to uniting Republicans is to focus on honoring our promise to the voters to repeal Obamacare and to focus critically on lowering premiums."

Tuesday's initial vote came amid boisterous chants of "shame" and “kill the bill” from protesters, with groups interrupting the proceedings before being escorted outside the Senate chamber.



Opponents of the Senate GOP's Better Care Reconciliation Act proposal — both Democrats and health care advocates — say planned reductions to Medicaid and other changes to existing health care policy will lead to millions of Americans losing or dropping health insurance coverage.

GOP defectors

With Republicans holding just a narrow 52-48 majority, and Collins and Murkowski voting against the motion to proceed, its passage was briefly in doubt as Republican lawmakers waited for Arizona Sen. John McCain and Wisconsin Sen. Ron Johnson to cast their votes.



Johnson was seen huddling with Senate Majority Leader Mitch McConnell and Majority Whip John Cornyn for several minutes before finally casting his approval. McCain, who was recently diagnosed with brain cancer, entered the chamber several minutes into the vote and received a standing ovation from his colleagues before approving the procedural step.