Here's a chart Ezra posted about how different age groups have moved around this year in terms of their Congressional vote.
It brings to mind Matt Taibbi's awesome description from a Tea Party rally of "A hall full of elderly white people in Medicare-paid scooters, railing against government spending and imagining themselves revolutionaries." Of course, the old people who abandoned Democrats and generated the downward motion at the bottom of the chart are by definition a swing-voting group and not hardened Republican base voters who likely are showing up at the rally. But the contradiction in an elderly group pushing an antigovernment ideology -- well, that's real.
If Republicans win power and limit their attacks to the Affordable Care Act (which, after all, leaves people over 65 in the same condition they were in before) they may not alienate these voters. But there are elements in their party that want to go after Medicare and Social Security. They can't do that and hold on to power, as Newt Gingrich and the Social Security privatizers learned.