Sen. John McCain, who was welcomed back to Senate with a standing ovation Tuesday, cast the deciding vote to defeat the so-called "skinny repeal" bill.

Senate Republicans voted Tuesday afternoon to advance to floor debate on their efforts to repeal and replace Obamacare with Vice President Mike Pence casting the tie-breaking vote.

Sen. John McCain returned to the U.S. Capitol today to cast a critical vote in favor of health care legislation less than a week after undergoing surgery and revealing he has brain cancer. McCain’s vote was essential as Republicans, who hold a 52-seat majority, scrambled to round up 50 votes on a motion to advance legislation to repeal Obamacare. Two GOP senators – Susan Collins and Lisa Murkowski – sided with all Democrats in opposition.

The vote came as Senate Majority Leader Mitch McConnell and President Donald Trump dared their fellow Republicans to block their seven-year campaign promise to repeal and replace Obamacare.

The next step is floor debate on the legislation to overhaul the Affordable Care Act, even though there aren’t any guarantees the votes are there to eventually pass it – and it’s unclear what a final bill will look like.

Trump, who has repeatedly said he’s ready to sign any repeal legislation, celebrated the vote, which creates a path to give him the major congressional victory that’s eluded the White House thus far.

“I’m very happy to announce that with zero of the Democrats’ votes, the motion to proceed on health care has moved past and now we move forward toward truly great health care for the American people. We look forward to that. This was a big step,” Trump said at a White House news conference.