The Financial Times has an excellent rundown today of the dynamics of Obama's VP considerations and prospects, and the reporter concurs that the announcement won't come until after the senator returns from vacation. Key passage:

It is even unclear whether Mr Obama has yet whittled his choice down to a shortlist. But a straw poll of Obama staff members and Democrats close to the campaign suggests that five or six names recur. Each is deemed capable of helping to neutralise one or more of Mr Obama's perceived weaknesses: inexperience, lack of national security credentials, the perception that he is aloof and his poor record of winning over blue-collar voters in swing states of the rust belt.

All are evaluated principally on their ability to help Mr Obama win in November, as opposed to the contributions they might make to an administration. In addition, good personal chemistry is ­essential. Mr Bayh is one of the most credible. A former governor of Indiana, he has the executive experience and mainstream credentials that many believe would help blunt voters' doubts about Mr Obama's relatively thin curriculum vitae and what some call his "exotic" background.

It's unclear whether reporter Edward Luce is deducing that "all are evaluated principally on their ability to help Mr Obama win in November" or whether that's what campaign staffers are telling him. If they are saying that, they should keep quiet. While everyone knows that's what candidates look for in their running mate, it's not the kind of thing you want out to be talking about.

In any case, read the whole thing.