My answer: Too much of the Republican base is now on Welfare and Medicaid to simply target these programs for elimination. There are very red counties in rural America where the majority of children are fed by WIC and the subsidized school meals programs. There are substantial numbers of very red counties where the local hospital is primarily financed by Medicare and Medicaid. Lots of absolutely die-hard Republicans now have older relatives supported in nursing homes via Medicaid. If Medicaid were eliminated, grandma -- who sadly has a tendency to wander off these days -- would be living at home.
Of course, it has always been true that a significant portion of people who voted for candidates that promise to cut government spending and entitlements are the beneficiaries of these programs. In 2010, a large number of people dependent on federal aid programs of various kind voted for Tea Party candidates who promised to eliminate these programs. So what happened between 2010 (and all previous elections) and now? Several factors:
1. More people generally, including more Republicans, have been dependent on social safety net programs longer. In fact, as the Republican base ages, many more of them become directly dependent on Medicaid as well as Medicare -- either for themselves personally or for older relatives. But even without this, long term unemployed and underemployed are dependent on a variety of welfare programs. Many of these do not anticipate finding anything close to full employment anytime soon. In 2010, a lot of these people expected to be employed soon and no longer need these programs. Now, not so much.
2. The Tea Party guys have shown they are actually serious about cutting this stuff. On the one hand, the base loves that. On the other hand, it is much less thrilling when it actually happens.
3. The more you take this stuff, the harder it is to fool yourself about the "us/them" nature of the program as an intrinsic. If neither I nor anyone else I know is on the program, then it is easy to believe it is for lazy losers. When I and everyone else I know is on the program, the problem cannot be the existence of the program itself. (Yes, I'm aware of the research on what happens when those who oppose abortions get abortions and the level of cognitive dissonance that can take place. A similar process happens here, but it expresses differently. When you and/or lots of folks you know get Welfare checks and you and your family get fed via WIC, you develop a different kind of internal narrative than a one-shot abortion that is kept secret.)
The result is a pivot to a new narrative. Welfare and other social safety net programs are not intrinsically bad (unless we are speaking to the wealthy and die hard libertarian wings of the party). But Obama will transform what is now a good program into a way to transfer money to them. So when we talk about cutting social safety net programs like Welfare and Medicaid, we don't mean to deserving people like you, only to the undeserving them.
This may seem rather thin especially as it totally reverses the longstanding rhetoric of the party. Also, any indifferent observer will note that the belief that there is somehow a deserving we and an undeserving they seems rather unlikely given the nature of the times and the nature of the programs. But keep in mind that the base wants to believe. Given the level of emotional investment in not merely embracing the conservative/Republican wing, but in demonizing and rejecting the Democrats, the base will grab at any even vaguely plausible construct to continue to vote GOP.
Kipling was wrong. While all good people agree, and all good people say, that all the people like us are we" and everyone else is "they," a trip over the sea -- rather than over the way -- does not change then mind of the stubborn believer.