They were waiting for this. They're arguing internally about whether they should have waited for Stevens to retire to push the bill through. The national movement had a strategy session and decided that South Dakota was the easiest place to make this play and then got to work. It's not like they had much to dismantle either; the only abortion clinic is in Sioux Falls, and South Dakota's Planned Parenthood system is so non-existent it's lumped in with North Dakota and Minnesota(home to some truly inspiring abortion doctors).
Supporters are pushing the measure in hopes of drawing a legal challenge that will cause the US Supreme Court to reverse its 1973 decision legalizing abortion.
The ACLU, NOW, NARAL, and all of us knew this was coming. We all knew it was coming. Why act so surprised? We probably could have stopped it if we'd been paying attention.