In other words, until fairly recently, poor rural whites were the key to winning in the South. So the parties competed over them, and very little happened with the flag. But in the past few years – and generational replacement is playing a part here as well – the South has become increasingly polarized, along with the rest of the country. Rural whites have begun voting Republican from the top of the ticket to the bottom, and Democrats have either written off the region or looked to form coalitions of minorities, urban liberals and suburbanites rather than of minorities, urban liberals and poor whites.
Because Democrats no longer see any electoral payoff in talking to guys with Confederate flags in the back of their pickup trucks, they no longer have any incentive to make even weak gestures toward keeping the flag around. Progressives are freed from their need to keep up their awkward dance with rural Southerners for the sake of maintaining some degree of power in the South (a dance that dates back at least to FDR’s reluctance to endorse anti-lynching laws). Polarization has forced them – and freed them – to explore new paths to power.
At the same time, it’s important to realize that most prominent Southern Republican politicians have roots in either the suburban or old establishment Democrat wings of the party. I doubt if Nikki Haley or Bobby Jindal grew up with much affection for the Confederate flag. The same goes for Mitch McConnell – who entered politics in Jefferson County (Louisville), an old Union town whose Republicanism was strong enough that it almost voted for Herbert Hoover in 1932.