Strategists in both parties now believe that the Romney campaign and the GOP in general completely missed a significant new reality: Many voters who chose to remain unaffiliated with either party are no longer shifting their allegiance from election to election, candidate to candidate. Instead, they are becoming increasingly partisan and predictable. That means that in order to win, each party must be far more ambitious in cementing its base — as Team Obama did — to win elections.

In fact, three weeks after the election, a shell-shocked senior Romney aide conceded: “We always said if we were winning independents in Ohio, we would win Ohio because that’s just the way it always was,” Romney political director Rich Beeson said. “They [the Obama campaign] were looking at a different dynamic, and their dynamic proved out.”

Indeed, the Obama’s campaign’s relentless voter modeling early on revealed that the voting bloc that was historically considered independent — and that had behaved as swing voters — was fast shrinking. Instead, most current unaffiliated voters were identifying with one party or the other — and voting that way.

“Moderates is a better way to define the people who swing back and forth … and those are the people who you’re going to fight over,” said Obama campaign manager Jim Messina at a recent POLITICO Playbook breakfast, when asked if the notion of independents deciding elections was passé. And by that definition, Messina claims that Obama prevailed with swing voters by 15 percentage points.