With no votes to spare, Vice President Mike Pence used his Constitutional power to cast a tie-breaking vote in the U.S. Senate on Tuesday, allowing Republicans to begin debate on a House-passed GOP bill that would overhaul the Obama health law, as Republicans scrambled to figure out how to cobble together a plan that could be ultimately approved in coming days by the Senate. The narrow victory was a big win for GOP leaders and the White House, as President Donald Trump had repeatedly pressed Republican Senators in recent days to keep their promise to act on Obamacare – but this was only an initial victory. In a speech just before the vote, and after a lengthy closed-door meeting of Republicans, Senate Majority Leader Mitch McConnell implored fellow GOP Senators to stick together, arguing they had promised the American people that they would make dramatic changes to Obamacare. “They didn’t send us here just to do the easy stuff, they expect us to tackle the big problems,” McConnell said. “We can’t let this moment slip by,”McConnell declared. Senate Majority Leader Mitch McConnell on health care: 'We can't let this moment slip by' https://t.co/7j5VjUmIM9 — CNN Politics (@CNNPolitics) July 25, 2017 Two Republicans voted against the motion to start debate: Sen. Susan Collins (R-ME), and Sen. Lisa Murkowski (R-AK). A number of other key GOP moderates voted for debate to begin, but did not guarantee they would support a final product. In the end, the crucial vote was cast by Sen. John McCain (R-AZ), who was just returning to the Capitol for the first time since being diagnosed with brain cancer; also pivotal was Sen. Ron Johnson (R-WI), who held his colleagues in suspense by waiting an extended period of time before casting a vote in favor of beginning debate. Johnson though has made clear his frustrations with the process, and with the details of the various GOP plans – it still isn’t clear how GOP leaders will find a solution that satisfies him, and several other Senators who voted to begin the health care debate. Johnson and McConnell spoke for an extended period of time on the Senate floor, mainly just the two of them – while other Senators waited to see what Johnson would decide. Democrats waited until Johnson and McCain had voted to vote; then each Democrat registered their opposition, to reinforce their stance on the GOP effort. Starting debate was difficult – now comes the tougher assignment of putting together a magic formula that can pass the Senate.