They just figured out that "pre-existing conditions" doesn't just mean that fat welfare queen who pumped out 10 kids before she was 30 and now has the beetus.
Statistically, "pre-existing conditions" means "old." But maybe not old enough for Medicare.
So now they're stuck between the group of fanatics who want to repeal every single word of it and create a huge, chaotic mess, the majority, who actually do want to improve things but disagree on how to do that, and the chumps who live in districts highly populated by people who would get axed under any of these schemes, who wish the whole thing would just go away.
They stand to lose all access to healthcare, or worse, pay so much that they can't afford even the most basic of it, despite Obamacare being a failure in need of improvement (e.g.: better marketing, lower prices, better quality, higher accessibility, and more importantly - someone in power getting it through their heads that a single-payer system was the best way to go this whole time. I could go on...).
Then again, Obamacare just lacks it all, especially thanks to their being no single payer and having to pay fees for not enrolling into a system that isn't truly affordable or easily accessible to begin with for a grand majority of this nation.