Mark Liberman at Language Log has an excellent analysis of politicians' slips of the tongue, focusing on this item from ABC News:

When introducing his running mate, Obama said, "So let me introduce to you the next president - the next vice president of the US of America, Joe Biden."

And then when it was Biden's turn to speak, the Delaware senator called the presumptive Democratic nominee "Barack America" instead of Barack Obama.

"My friends, I don't have to tell you, this election year the choice is clear. One man stands ready to deliver change we desperately need. A man I'm proud to call my friend. A man who will be the next president of the United States, Barack America," Biden said, per ABC News' Sunlen Miller.

Liberman points to particular linguistic reasons why these particular kinds of slips are commonplace, and concludes — rather more categorically and forcefully than I would, but on balance basically soundly — with this:

With respect to speech-production blunders all across the political [spectrum], our perspective has been consistent[]. Everyone commits speech errors, even professional talking heads, and anyone who makes a big deal about particular examples is either a fool or a hypocrite. Since fatigue, stress, and complex ideas all promote speech errors, you can depend on political rhetoric to provide plenty of occasions for foolishness and hypocrisy.

Responding to my post quoting Mark Liberman (Language Log) on politicians' slips of the tongue -- here, Obama's and Biden's slips, a commenter responds:

These studies seem to come out at convenient times. When its a republican who exhibits slips of the tongue, we get "Bushisms" as evidence of lack of intelligence. When a Democrat comes along with the same problem, its "Oh, well, it doesn't mean anything, everyone does it."

When it looked like the Democrats were a lock on the Presidency, all of the sudden academics were proposing a "cease fire" in the judicial confirmation wars.

These all remind me of the "homeless rediscovery" watch from Opinion Journal.

Now I'm happy to agree that academics do tend to, on average, lean left; and academics, like other people, on balance have their share of partisanship. But before you accuse a particular academic of partisanship, wouldn't it be good to actually look a little at his track record, rather than simply inferring his behavior from his profession?

As it happens, the Language Log post asserted that "With respect to speech-production blunders all across the political [spectrum], our perspective has been consistent," and included links to some earlier posts on the subject. But even if the commenter hadn't noticed that, it would have been trivial to just Google "language log" bushism or "mark liberman" bushism. Either approach would have made clear that Liberman has indeed criticized Bushisms often (and in my view quite persuasively), and thus indeed seems to be quite evenhanded on this subject. The commenter's accusations were unfounded, as many inferences from a group's behavior to an individual member's behavior tend to be.