We’ve seen this movie before. Republicans, after a secretive drafting process, finally unveil a health care bill. But the initial reaction is tepid, with both moderate and conservative Republicans expressing “concerns” and demanding changes to the bill.

That’s what happened when the House Republican leadership released its health care bill, the American Health Care Act, in March. And that’s what happened on Thursday, when Republican Majority Leader Mitch McConnell released the Senate’s version of a health care bill, called the Better Care Reconciliation Act.

Soon after the BCRA was officially released, four conservative senators — Rand Paul, Ted Cruz, Mike Lee and Ron Johnson — issued a statement saying that they were “not ready to vote for this bill,” although they also said they were “open to negotiation” about it. This was hardly the only opposition to the bill, however. According to The Washington Post’s whip count, five other relatively moderate Republicans — Susan Collins, Lisa Murkowski, Dean Heller, Rob Portman and Shelley Moore Capito — said they had serious concerns with the bill, ranging from its defunding of Planned Parenthood to its cutting of funds for Medicaid. That would seem to put McConnell in a difficult spot: Assuming no Democrats vote for the bill, McConnell can afford to lose only two of his senators. But he already has nine senators objecting to the bill from various directions.

We also remember how that other movie ended, however. After a false start in March, when House Speaker Paul Ryan pulled the AHCA from the House floor, Republicans regathered to pass their bill in May by a 217-213 majority.

It’s tempting, therefore, to assume that the same process will play out in the Senate and that the BCRA will eventually pass after a few weeks of drama. When the ink is still drying on the bill, as it is right now, Republican senators have lots of incentive to express their concerns, whether to stake out a negotiating position or to posture before their constituents. McConnell is a skilled vote-whipper, however, and the Senate has generally toed the party line in support of the GOP agenda and President Trump. And even if the bill isn’t exactly the one that senators might want, it’s still in line with longstanding GOP policy objectives.

So all of this probably ends with a big signing ceremony in the Rose Garden — and millions of people losing their insurance, right?

Well, maybe. Betting markets give roughly even odds that key provisions of Obamacare, such as its employer mandate, will be repealed before the end of the year. I don’t know what probability I’d assign to the bill’s passage myself. But I do think it’s worth pausing to take an inventory of some of the differences between the House’s situation and the one the Senate now faces. There are quite a few of these — some of which make the bill more likely to pass and others less so:

Finally, there’s the wild card of Trump, who reportedly called the House bill “mean” but praised the very similar Senate bill on Thursday. I’m not going to score that in either direction.

So to tally things up, that’s four “helpfuls” and five “harmfuls.” Furthermore, the first “harmful” — that McConnell can afford far fewer defections than Ryan had — is especially important. Overall, the Senate bill faces a somewhat different and probably also more difficult set of obstacles than the House one did. Therefore, I’d guard both against interpretation that the bill will necessarily pass the Senate because it passed the House. At the same time, Ryan and House Republicans overcame some of the same obstacles — and if that precedent isn’t dispositive, it’s at least highly relevant. Among other things, we know that early whip counts aren’t all that reliable and major legislation often follows a bust-and-boom cycle in which it seems to be falling apart only to come together in the end. Neither Democrats nor Republicans ought to be taking much for granted.