Obama has said his position on Marriage Equality has been evolving, probably not. Public opinion however, has been evolving, as have the demographics. The old, rigid, fearful of gays, generation of voters has been dying off.
They’re being replaced by a generation that began voting right after Y2K. Remember the computer panic by that name? It was a real threat, and not just a hoax, but not the end of the world the way the same people who have lately been selling gold made it out to be. (BTW, gold dropped under $1600/oz today, it could be on the way down to $700)
Computers have come along way since Y2K, and they know what you think, literally. Maybe better than you do. Obama’s campaign planners are using computer power that is running algorithms on data sets that were unimagined back when we worried that the year turning over zero would crash the entire world.
All the small but trackable moves that Obama’s people have made over the past couple of weeks, and the predictable but also trackable moves that Republicans made in response, gave them the numbers they wanted to see.
I know it sounds like voodoo, but it really does work. The computers have a pretty good idea within the margin of error (of course) exactly how many votes are to be gained and lost by the President’s announcement, right down to the city block.
They know how many people will be motivated to go out to knock on doors and how big their donations will be. They also know how many Republicans will be affected, as more and more them discover that their own families are rife with gay folk. Just how much does it affect them having a candidate they really don’t like to begin with reflexively behaving like a 19th century bigot.