US Republicans have pulled off a narrow victory to move closer to a repeal of Obamacare.
The Senate voted 51-50 on Tuesday to move forward with a debate on health care reform, even though it was not clear what new measure the body will be considering. Vice President Mike Pence cast the tie-breaking vote.
Republican Senators Susan Collins and Lisa Murkowski were the only two GOP members who joined Democrats in voting 'no' on the motion to proceed.
Before the voting began, protesters in the Senate's public gallery chanted "Kill the bill" and "Shame! Shame!", the Associated Press reported.
Republican Senator John McCain, who was diagnosed with brain cancer last week, returned to the Senate floor to vote in favor of moving the debate forward. His appearance was met with a standing ovation.
"I voted for the motion to proceed to allow debate to continue and amendments be offered," McCain said. "I will not vote for this bill as it is today. It's a shell of a bill right now. We all know that."
The Senate GOP has dealt with several setbacks, including not having enough votes for its original plan to repeal and replace aspects of Obamacare or for a straight repeal, but President Trump has pushed for Republican lawmakers to make progress on one of his biggest campaign promises.
In a statement released on Tuesday, Trump said he applauded senators for "taking a giant step to end the Obamacare nightmare."
"As this vote shows, inaction is not an option, and now the legislative process can move forward as intended to produce a bill that lowers costs and increases options for all Americans," the statement said. "The Senate must now pass a bill and get it to my desk so we can finally end the Obamacare disaster once and for all."
Trump thanked Senator McCain on Twitter for returning to D.C. "for such a vital vote."