Mark Penn declared today that Barack Obama "really can't win the general [election]." Of course, it's silly to say that Obama or Clinton "can't" win the general. There's not even good evidence to suggest that Obama is less likely than Clinton to win the general. Currently, the RCP poll average has both defeating John McCain by an average of 1.5%. Before the last couple weeks, when McCain and Clinton have both been making mutually-reinforcing attacks on Obama nearly every day, Obama was running well ahead of Clinton in those head-to-head matchups.

Both Obama and Clinton have significant drawbacks as general election candidates. I think Obama's potential -- that is, in situations when a high-profile Democrats is not reinforcing the GOP message every night -- is much greater than Clinton's The basic fundamentals are best captured by the Gallup Poll's favorable/unfavorable rating, which is the basic measure of a politician's popularity, for Clinton and Obama. Here's Clinton:

And here's Obama:

That's an enormous difference -- a thirty-point gap. Obama has plenty of flaws as a general election candidate, but they're not as deeply-rooted as Clinton's.

As I said, Obama was running well ahead of Clinton in head-to-head matchups a few weeks ago, and now they're tied. After several more weeks of Clinton reinforcing McCain's message against Obama, Clinton will probably be performing better than Obama against McCain. This is the point I made in my TRB column. She needs to convince the remaining uncommitted superdelegates to split for her by about a 2-to-1 margin. The only way she can get a split like that is if she can persuasively argue that Obama is unelectable. And the only way she can do that is to make him unelectable. Some people have treated this as an unfortunate byproduct of Clinton's decision to continue her campaign. It's actually a central element of the strategy. Penn is already saying he's unelectable. It's not true, but by the time the convention rolls around, it may well be.

--Jonathan Chait