1. Susan Collins and Lisa Murkowski
The simplest way to describe the unexpected loss dealt to the long, torturous campaign to repeal the Affordable Care Act is that three Republican senators refused to endorse the latest bill, which would have removed the requirement that people buy health insurance, thus likely destabilizing the insurance market. Of those three, two objected to the bill on its merits.
Alaska's Lisa Murkowski has been opposed to many elements of ACA repeal from the start. In June she said she wants to leave in place the Medicaid expansion and rules forcing insurers to cover people with preexisting conditions, two key planks of the ACA. She also has refused to block Planned Parenthood from receiving federal funds, which other Republicans want to make part of any healthcare bill. She's maintained these positions even after the Trump administration made barely-veiled threats that her continued opposition would lead to the Department of Interior moving to hurt Alaska's energy economy somehow.
Maine's Susan Collins is also a moderate who shares those concerns—and, the New York Times noted, may be worried that a repeal of the ACA would hurt Maine's older population especially. Then there's the possibility she might run for governor in 2018; presumably, it would be hard to campaign for that office after voting for a bill that would lead to Mainers losing their insurance.
2. John McCain
Next to Collins and Murkowski, Arizona's John McCain's opposition to the bill was fairly mild, even though his vote was the one that got the most attention for being unexpected. In a statement following his vote, McCain condemned the ACA but said that he wanted to replace it with "a solution that increases competition, lowers costs, and improves care for the American people." To do that, he added, "We must now return to the correct way of legislating and send the bill back to committee, hold hearings, receive input from both sides of aisle, heed the recommendations of nation's governors, and produce a bill that finally delivers affordable health care for the American people."
In other words, McCain's problem was mostly with the process that's surrounded the bill. It was written hastily—literally at lunch on Thursday—and derided by several Republican senators. Some of these Republicans only supported it on the condition that the House would reject the bill. The idea was that then the House and Senate could compromise on some other bill, but the strategy of voting for a bill while demanding that it fail was the sort of insane move that only makes sense in the current Congress. (It's also far from clear what that magical compromise bill would even have in it, given that other options were shot down by the Senate earlier this week.)
McCain wants the ACA repeal without the procedural insanity, which seems like a mild, even conservative, position to take. It's only the extremism of the rest of the Republican Party, the thirst for anything that could be called "repeal" at any cost, that makes him an outlier.
3. Donald Trump
The president took to Twitter to criticize the vote, but while he tries to shift the blame for the failure to the Senate, it's worth looking back at how ineffective he's been in the healthcare debate. As a candidate, Donald Trump made noises about a healthcare reform that would provide "insurance for everybody" and would lower costs, but those vague promises just made the actual Republican policies—which would result in fewer people having insurance and raise premiums on many—seem more starkly cruel and contradictory.
Trump seemed to have few definite ideas about what healthcare reform should accomplish. Though he celebrated the passage of the House bill in May, weeks later he called it "mean," echoing criticisms of the bill from Democrats. The ACA only passed after intense efforts from the Barack Obama White House to work out details of the bill and persuade fence-sitting Democrats. It's unclear if a similar push from a more competent Trump team could have brought the holdouts onboard, but it might have made the process smoother at least and clarified where the president stood on things like Medicaid expansion and pre-existing conditions.
4. The Resistance
As Republicans in Congress worked on the various iterations of the repeal bills, liberal activists were pressuring vulnerable legislators to vote no on anything that scrapped the ACA. Mass phone calls, town hall protests, and demonstrations didn't stop the House from passing its bill, and didn't stop some senators facing reelection, like Nevada's Dean Heller, from voting for the last effort in the Senate.
But that activism may have given Collins and Murkowski confidence that they could oppose repeal without risking their political futures. It also likely slowed down the process, which Trump promised would be quick. And the longer the debate dragged on, the less popular repeal became.
5. The Republicans
The real problem at the heart of the repeal effort, however, was that after seven years of condemning the ACA Senate Republicans didn't have a replacement plan, or even a set of principles that they could build a replacement around. Various ideas were proposed by Republicans before the 2016 election, but nothing unified the party—tellingly, the man who became the Republican presidential nominee basically ignored the specifics of the issue, and the base was completely fine with that.
As the 2017 debate began, right-wing senators demanded that the ACA be fully repealed, but moderates wouldn't sign on to that position because of how many people would wind up freshly uninsured as a result. Conservative healthcare wonks were warning that the problems in the system were complicated and difficult to address. Sensing that whatever they came up with would be unpopular, House Republicans initially hid their legislation in a basement.
The repeal debacle shows the dangers of campaigning against an existing policy without having a replacement in mind—the problems don't come when you lose, but when you win and have to govern.
Follow Harry Cheadle on Twitter.