There are whispers that Barack Obama has already made his vice-presidential choice. Rumor has it that Evan Bayh is out and that Joe Biden's stock is rising. (Jake Tapper reports that Obama slipped in a mention of Biden during his campaign speech this morning in Florida.)

Forget the list of contenders for a moment, and let us also dispense with the precondition that Obama should pick somebody able to take over should anything ever happen to him by assuming he would not have any finalists on his list unable to do the job. What, then, are the one or two criteria -- policy, political skill set, demographic draw -- Obama most needs in a running mate? I'd like to hear from Salon readers on this score before we know the pick, and since that could come at any moment, now is the time.

To simplify things, as we did with the ranking of the Bayh/Biden/Tim Kaine/Kathleen Sibelius discussion two weeks ago, here is a nonexhaustive list of four traits:

1. Can be a good attack dog and hammer John McCain.
2. Offers a working-class, rank-and-file appeal to those parts of the coalition with whom Hillary Clinton thrived.
3. Potentially delivers a state.
4. Is strong in policy areas where Obama is not.

For my money, politics matters more than policy, and I think Obama's "new politics" still needs an old-fashioned, attack-dog edge to it. There is lot to criticize McCain about during the past eight years from an administration he midwifed into power. Obama cannot just go positive, like John Kerry did four years ago. So, for me, the criteria are already rank-ordered in the list above.

Your turn.