Washington (CNN) For weeks on end, his colleagues outright rejected his attempts to get to 50 votes.

Finally, Mitch McConnell changed his approach: We'll make this a free-for-all.

A dramatic procedural vote on the Senate floor Tuesday afternoon to begin the debate on a bill to dismantle Obamacare marked a kind of bitter victory for the Senate majority leader.

McConnell suffered multiple setbacks this summer as he searched in vain for 50 Republicans who would back a GOP health care bill, but it was only when McConnell stopped pushing for members to get behind one comprehensive Senate bill that the impasse broke, just barely.

The motion to proceed barely passed 51 to 50, and only with help from Sen. John McCain, the Arizona Republican who traveled back to Washington just days after surgery for brain cancer, as well as Vice President Mike Pence, who served as the tie-breaker.

"I hope everyone will seize this moment," McConnell implored his colleagues from the Senate floor just hours before the vote began. "Only then can we open up a robust debate process. Only then will senators have the opportunity to offer additional ideas on health care."

The past month hasn't been easy for McConnell. He was forced give up on a repeal bill last week after it was clear he didn't have the votes -- the second proposal that he couldn't get enough support for. The motion to proceed vote was not originally expected to go anywhere, but an intense lobbying push by leaders, and help from the White House, got it done.

In the hours leading up to Tuesday's vote, McConnell made fresh promises and unveiled a complicated, four-pronged approach to skeptical colleagues that assured them their most urgent priorities would get a fair hearing on the Senate floor. All they had to do was vote to start the debate, he said. And in the end, enough Republican members came to believe that they would get something for their support.

"These are the moments legislatively when you get creative. We're getting creative," a GOP aide involved in the health care process said.

It worked.

Kentucky Sen. Rand Paul, who even until Monday evening was complaining that leadership had not given him the time of day and that it was difficult to imagine how he could possibly get to a "yes," had a sudden change of mind.

"This morning, @SenateMajLdr informed me that the plan for today is to take up the 2015 clean repeal bill as I've urged," Paul wrote on Twitter. "If that is the plan, I will vote to proceed to have this vote."

Sen. Mike Lee of Utah, a holdout on previous repeal and replace bills that McConnell had attempted to garner support for, also came around after being promised an amendment crafted by Lee and Sen. Ted Cruz that would allow some insurance companies to offer plans unregulated by Obamacare.

And according to an aide Sen. Rob Portman, the Ohio Republican got to "yes" after McConnell promised him that there would be a vote on a proposal adding $100 billion more to the stability fund that exists in an earlier repeal and replace bill. That proposal would help individuals on Medicaid expansion and other low-income people purchase health insurance under the GOP health care plan. It is a priority for Portman, who hails from a state that expanded Medicaid under Obamacare.

But all Republicans are aware of this reality: there's hardly any guarantee that what they want will be included in the final package. In fact, because there is no Congressional Budget Office score on some proposed amendments, it's possible that passing those proposals would require 60 votes rather than 50.

With Democrats unwilling to help, such amendments would fail.

The 2015 repeal-only bill that Paul has advocated for wouldn't require 60 votes, but it is expected to die on the Senate floor, with enough Republicans who have already publicly opposed to it.

Working in McConnell's favor in recent days was almost a desperate desire among some of his colleagues to get to a "yes," even as the political dynamics in the conference remained the same.

Moderates still said they wanted to make sure that people back home wouldn't be hurt by the GOP's repeal bill, wanted more money for low-income people and advocated for softening the transition off of Medicaid expansion. Conservatives maintained they still wanted to see more regulations repealed.

But, pressure mounted from outside groups like Heritage Action, making it harder for conservatives like Lee to stay a "no."

The White House also turned up the heat, dispatching key emissaries like Medicare and Medicaid chief Seema Verma to meet with moderate senators and try to convince them that the cuts wouldn't be that bad for their states.

According to Portman's aide, Portman worked "extensively" with Pence, Verma, Health and Human Services Secretary Tom Price and colleagues to come up with the proposal he asked McConnell for.

Leadership also sold members on the fact that despite what happens over the next few days on the floor, if Republicans were willing to vote "yes" to get to a House-Senate conference, any outstanding issues could also be worked out during that process.

In the end, only Republican Sens. Susan Collins of Maine and Lisa Murkowski of Alaska couldn't be convinced by McConnell's new tactic.