Jonathan Bernstein makes an interesting point in his comment on the Rice-for-VP distraction:

What I’ll add is that a secondary reason some have cited for why Rice won’t be the pick — that choosing her would remind people of the unpopular George W. Bush presidency — doesn’t really hold up. Nor does it hold up for Rob Portman, who headed the Office of Management and Budget under Bush. Sure, Democrats would have an excuse to talk about Bush, but it’s not as if Democrats need some sort of license to talk about him, and I think it’s utterly implausible that any voter who otherwise would believe that Romney’s policies would differ from Bush’s would be convinced otherwise by the running-mate choice.

It seems to me that the difference between Rice and Portman in their connection to Bush is that only one of them is very closely identified with Bush’s foreign policy and the administration’s failures abroad. Portman didn’t oppose any of Bush’s decisions (neither did most Republican politicians), but he wasn’t one of the people helping to craft those decisions, implement them, and then publicly sell them. Portman worked in the administration at OMB, but he did so after the worst of the fiscal damage had already been done. Insofar as the association with Bush is politically radioactive, Rice is far more radioactive because of her much closer, longer “exposure” to being an important figure in the administration.

The key difference between Rice and Portman is that she would greatly reinforce the impression that Romney’s foreign policy is a return to the Bush era (which it clearly is), and Portman isn’t as closely identified with Bush’s foreign policy record to have the same effect. Rice has all the negative associations that go with some of her worst statements while working for Bush, including her infamous threat-hyping claim that “we don’t want smoking gun to be a mushroom cloud” and her appalling description of the bombardment of Lebanon as the “birth pangs of a new Middle East.”

Portman certainly doesn’t represent a break with the Bush administration. Like Paul Ryan and almost all other House Republicans, he voted for the Iraq war. Also like Ryan, Portman voted for all pieces of major legislation supported by Bush, and the main reason he doesn’t have quite as many bad votes in his record is that he didn’t stay in the House.

Bernstein makes a fair point that voters not already inclined to think of Romney as a return to the Bush era won’t be convinced by the running mate alone. However, the choice of running mate can draw more attention to this or minimize it. A Rice selection (which we all agree isn’t happening) would definitely draw much more attention to the similarities between Romney and Bush than many of the other possible candidates.