My colleague Josh Patashnik and quasi-colleague Nate Silver have done a public service by placing Senator Evan Bayh in a proper ideological context. Notwithstanding Bayh's image as a squishy moderate and occasional crusader against the left, his voting record turns out to be relatively progressive. And that goes a long way to making liberals like me feel more comfortable with the possibility of Bayh becoming Barack Obama's running mate.

But ideology isn't the only reason some of us are wary of Bayh. Another is his history of accomplishment--or relative lack thereof. I've been reading clips and calling around Captiol Hill lately, looking into Bayh's record. And I'd be hard-pressed to name an issue on which he's really distinguished himself. There's no legislative agenda or intiative for which he is particularly famous. And there are no episodes in which he demonstrated particularly astute judgment.

Bayh may be smart, dedicated, and thoughtful.  But the singular achievement for which he seems to be known is that he's managed to get elected--and remain popular--in a state that's not generally fond of Democrats. And even that is something for which he can't take full credit himself, given that he is part of an Indiana political dynasty. If he had been born "Evan Smith" instead of "Evan Bayh," would he have pulled this off? 

This matters because--as I've written before--I think the most important criteria for picking a running mate is choosing somebody capable of serving as president in a time of crisis. It's particularly important when choosing somebody as young as Bayh, since--if all goes well--he'll become the heir apparent eight years hence. Accomplishments don't necessairly equal readiness to be president. But, all other things being equal, I'd argue they are a decent indicator.

Admittedly, not everybody agrees with that assessment. For many people, political considerations are paramount. Obama needs to pick somebody who can help him get elected; everything else is secondary.

But how much would Bayh help? Precisely because Bayh has no other claim to fame, pundits will jump on this as proof that Obama picked Bayh in order to overcome a political liability. That, in turn, could undermine one of Obama's biggest claims--namely, that he's not just another politician.

It's possible, of course, that appearing to act politically is a small price to pay, given all that Bayh would bring to the ticket. Bayh, who is to politics what Wonder is to bread, might really make a lot white voters feel more comfortable about backing Obama. And there's a decent chance he would help put Indiana in play, which is no small thing. 

Still, the political calculus doesn't look as simple as it seems. And that makes me wonder whether, somewhere in the party, there's a better candidate to be chosen.

--Jonathan Cohn