The obvious thing to say about the Ryan pick is that Romney is following the Dole playbook: when nobody is particularly enthusiastic about your candidacy, pick a VP candidate who enthuses the base but is also a known quantity who plays well with the media. Dole’s choice of Kemp both coincides with and reinforced the message of his announcement of an economic plan that consisted mostly of across-the-board tax cuts – which had not been a feature of Dole’s candidacy (or career) before that. The Ryan pick follows Dole’s example here as well. Romney spent most of the campaign running as vaguely as possible, and only relatively late in the game announced that the new centerpiece of his economic plan was an across-the-board cut in tax rates (which he claims he would pay for by eliminating loopholes). As with Dole and Kemp, the Ryan pick reinforces this message.
Kemp didn’t seem to do Dole much good, and I don’t expect Ryan to do Romney much good, but counterfactuals are really hard to prove, so who knows.
The other thing I note about Republican VP picks is that, since Reagan, every VP choice by a Republican nominee has been, in some fashion, a base-pleasing move to the right. Bush Sr. picked Dan Quayle to reassure movement conservatives that he would keep faith with the Reagan religion and that they would have a voice in the White House through which to reach him if he didn’t. Dole picked supply-side hero Kemp. Bush Jr. picked Cheney, largely to provide heft and ballast to the ticket, but also because Cheney had a rock-solid conservative record in Congress. And McCain picked Sarah Palin, who, at the time of the pick, was ideologically undefined, but who was expected to excite conservatives because of her background and life story.
Interestingly, the Democrats also have a history over the same period of picking running mates perceived to be to their right, or at least from the rightward flank of their party. Dukakis picked Bentsen. Clinton picked Gore – darling of the DLC set. Gore picked Lieberman. Kerry picked Edwards (who, though he ran to the left in 2008, was perceived as a relatively more conservative Democrat in 2004). And Obama picked Biden, who was certainly perceived as being to his right on foreign policy.
The last time the Republicans picked a VP candidate specifically intended to moderate the conservative image of the nominee was 1980. The last time the Democrats picked a VP candidate specifically intended to balance their ticket in a leftward direction was 1976.
Make of that what you will.