After winning the presidency, and already having majorities in the House and Senate, the GOP was supposed to be poised to repeal Obamacare on the first day of President Trump's term. Somehow, that didn't happen. BECAUSE REALITY IS A BITCH!
The GOP can't wave their hands anymore and fling pixie dust. They have to seriously crunch numbers, and it hasn't been going well for them. They can drop coverage for millions of people, they can zap the mandate and see cost rise even higher, they can repeal the taxes and blow up the deficit. What they can't do is figure out how to make a program cover more people and cost less. I wonder why not. Maybe not enough pixie dust.
Extras. Problems with repeal and replace (with less snark). True believers among Congress just don't understand the delay. Trump makes another promise about the replacement, sprinkled with prodigious amounts of manure-scented pixie dust.