So, the conversation has moved on, but whatever.
The House and Senate have to pass the same bill for it to become law. The House passed its version last year. The Senate passed its version on Christmas Eve. Normally they’d go to conference, differences would be hashed out, and a compromise between the Chambers would have to be repassed by both.
Due to GOP obstructionism, esp. after the accession of Sen. Brown and the loss of the 60 vote majority, this was no longer feasible. But both bills continued, having been passed by their respective Chambers. The House bill was too liberal for the Senate, and the House didn’t have the votes to pass the Senate bill because of a combination of its centrism turning off the progressives and its abortion language being not exactly what the pro-life Dems demanded.
The solution was a reconciliation bill, that is, a bill using special Senate rules about bills affecting the budget to allow the package of “fixes” to go through with a simple majority vote. (Since the Vice President can break ties in the Senate, that means 50 + Biden, if needed.) This particular reconciliation bill is based on but not identical to the President’s draft of desired changes.
There was still consternation, though, because as the rules were interpreted, the Senate couldn’t vote on the fixes until the underlying bill became law, and the House didn’t trust the Senate to do it. However, the Senate Majority leader promised that he had the votes to pass it, and committed to taking up the bill first thing. This convinced several of the progressives on the fence, while the promised Executive Order either convinced the pro-life Dems or, in my opinion, gave them a way to save face. So on Sunday night, the House passed the Senate version of the bill.
Then there was the GOP-led motion to recommit, which basically is a way of calling “backsies” on a bill you just passed. Knowing where the fulcrum was, the GOP structured this motion to specifically hammer the pro-life Dems. But there was little chance, and as much as Bart Stupak got me pulling my hair out over the last several months, he gave a thunderous speech on the Floor denouncing this as a big con, and it failed. The House then passed the reconciliation fixes. (AFAIK, the GOP didn’t press a motion to recommit on the reconciliation bill; it would have failed anyway.)
So now this underlying bill had been passed by both the Senate (in December) and the House. That’s all (ha!) that was needed, and so it was eligible for the President’s signature. Yesterday he signed it, and as of that moment it became the law of the land. (And yes, it’s a big fucking deal.)
As for the reconciliation fixes, they’ve only been passed by the House so far (the Senate’s working on them literally this minute). A few things can happen – first, the Senate can pass it, as is. This is the most likely, but the GOP is applying a whole bunch of dilatory tactics, including “when did you stop beating your wife”-type amendments, so it’ll take a while. If this happens, then it too will be ready for presidential signature, whereupon it will also become law, modifying the law as it currently (that is, since yesterday afternoon) exists.
Another possibility is that there will be some changes, possibly because of the arcane rules which allow this bill to be considered under majority rule, instead of subject to the extraordinary GOP filibuster. If that occurs, then the two Chambers will have passed different versions, and so the House will either need to pass the amended version, or (exceedingly unlikely) it’ll go to conference and both Chambers will have to pass the compromise (although still under simple majority rule). This will be a pain, but it would almost certainly pass the House, be signed, and become law.
The most unlikely – really there’s exceedingly little chance – is that, for whatever reason, the reconciliation bill doesn’t get passed. Either it’s blocked by Senate budget rules, or Senate amendments are too significant and can’t get support in the House, or something else batshit happens. And if that happened, it would never become law. But that doesn’t change that the main Affordable Care Act is already the law. The reconciliation bill would just make some amendments to what is already signed, sealed, and delivered, and its failure can’t erase what has already been enacted.
(N.B. This is, of course, the simplified version!)
–Cliffy