Which party's electoral/demographic coalition is more unstable?

[Spanish Moss]

Republicans. Soccons are not going to keep sharing the same party with libertarians. One or the other has to crack.

libertarians don't actually exist outside of the internet

Really? More than 1 million people voted for Libertarian Party in the congressional elections in 2010, to say nothing of members of the Republican Party with libertarian leanings. Libertarianism is a very real, and btw strengthening, force in American politics.

In the 20th century, the extremist solution to economic decline was fascism.  In the 21st, it's libertarianism (aka, "privatized fascism").  And if things don't truly get better, I see it rising like fascism.  But unlike fascism, it will make living standards worse - not better - and will probably not last but for more than a few years.