the center absolutely is not "moving left". socially yes - but even then only in some ways, abortion is still basically an even split - but fiscally it's the exact opposite. Nixon widely expanded social safety nets and founded the freaking E.P.A. that could never happen in the age of Grover Norquist.
Well, I don't think that fiscal issues are that central. But whatever happens, the government will expand as a function of time. It doesn't matter who is in change, as far as I can see:
You can see from the graph that, not only is it growing in absolute terms, but, allowing for some cyclical variation about trend, its even growing as a share of income!
I won't post more graphs, but I think that you'll be hard pushed to find any evidence that our contemporary fiscal conservatives have had a material impact on the size of the American government.
As for the rest, take any dimension you like, cycle back 50 or 100 years and tell me if society has become more liberal or more conservative. In every dimension I can think of, the answer is that society has become more liberal.
and i'm sorry, but the issue is precisely that the GOP let the fringe in (in fact, went out and recruited them via the astroturfing that kicked off the Tea Party).
And who were this "fringe" voting for before they were let in by the GOP? They were voting for the GOP. The problem is that to be a moderate today, which is what you probably are if you are a competent politician or bureaucrat, places you much further away from the "crazies", i.e. the GOP's traditional base, than it did in the past. This becomes less of a problem, I suppose, if the GOP simply ignores them. I mean, who else are they going to vote for?