Donald Sensing is worried about judicial activism, so worried that he's afraid that within a generation the US will be a tyranny. He feels that neither of the major parties has a strong position against judicial activism. The Republicans at least pay lip service to judicial restraint, and Republican judicial appointees generally show a greater respect for the Constitutional text (see Scalia and Thomas), but Sensing and others can point to plenty of counterexamples. They make the argument that the Republicans are only complaining about judicial activism because liberals are in charge of the judiciary, and that if they were in charge (and in a few cases cases where they have been in charge), they would be doing the same thing as the liberals. Maybe the Republican talk about judicial restraint is just lip service, and they aren't really interested in reforming the judiciary.
So what? At least they give it lip service, and while that may not be enough, it's a starting point. It's in Republican self-interest to oppose judicial activism, because they never seem to win those games. Maybe if they could make enough judicial appointments, they could start to win, but it doesn't look like that will ever happen. Democrats always appoint liberals, but Republicans never have much luck getting conservatives appointed. Senate Democrats vote against any Presidential appointee whose politics they can impugn, and they're quite good at that, while Republicans usually feel it's their duty to approve any appointee who's qualified. This difference in philosophy means that Democratic presidents can pack the courts with liberals, while Republican presidents only seem able to get moderates through.
The Republican position, even if it's not sincere, has drawn those who are sincere about it to the Republican banner. Today, those who want judicial restraint have no choice other than the Republicans. And since these people are now part of their base, the Republicans are more responsive to the sentiment. Those who believe in it are becoming more important in Republican circles, both as politicians and opinion writers. Read National Review. I'm fully convinced most of the writers believe in judicial restraint as a matter of principle, often arguing against Republican pet causes that they believe overreach the bounds of government and the courts. The gay marriage issue has galvanized the Republican base, but a large number of them, including myself, are arguing that the solution is not to ban gay marriage itself, but to stop the out-of-control judiciary which would impose it on us. It is Republicans who are proposing a bill which would give Congress a means to overrule the Supreme Court. This won't stop government overreach in general, but it would at least ensure that our elected representatives get the last word.
Constitutionalists won't find either of the major parties perfectly in tune with their goal. Judicial activism is just too accepted in our culture for either party, which are after all broad coalitions of many different political movements, to be totally against it. But they're going to have to choose the lesser of two evils, and they're only kidding themselves when they say that there's no difference between the two parties.
Update: I fixed the link which was supposed to point to my post on the Republican bill but instead led to a post by Donald Sensing. (Not that it was a bad post, just not what I was referring to; it's the same as the one which appears earlier in this post.)
New Post: More on the ongoing discussion above.