Politico provides the best analysis of the behind-the-scenes action in what led to where we are:
The rebirth of the reform effort is the result of a little luck, insurance company avarice, a subsiding of post-Brown panic among party incumbents and the calculation by many Hill Democrats that going small or giving up was just as politically perilous as going big.
But the main reason the bill has made it to the floor has as much to do with the complex, occasionally tense, ever-evolving partnership between the first African-American president and the first female speaker.
and
Publicly, the White House seemed to send a different signal each day.
In the space of two weeks, Obama or his top advisers suggested breaking the bill into smaller parts, keeping it together in one comprehensive package, putting it at the back of legislative line and needing to “punch it through” Congress, as Obama himself said at one point.
At a fundraiser in early February, Obama described the “next step” as sitting down with Republicans, Democrats and health care experts, describing a process that could take weeks, if not longer. He also seemed to acknowledge for the first time that Congress may well decide to scrap health care altogether — an admission that blunted his repeated and emphatic vows to finish the job.
Behind the scenes, Obama had, in fact, already settled on a strategy.
He would invite Republicans and Democrats to a summit, to give them one last chance at compromise, knowing they wouldn’t budge. And privately, he had decided that his favored approach was a comprehensive bill.
However, what I've been thinking about over the last few days is the similarity between how health care reform, Hillary, and McCain were handled by the Obama team. See my from October 08 where I mentioned an Andrew Sullivan article of how Obama's calm (and sometimes perceived weakness) lures the opponents into a false sense of victory and incites them. It was easy to doubt him during the primary (why wasn't he more aggressive against Clinton) and during the Summer of 08 (why did he take that stupid trip to Europe) but in all cases (assume this goes through) he pulls it off.