The always insightful Jonathan Chait makes the definitive, devastating case against Howard Dean becoming chairman of the DNC:

The conventional rap against Dean as DNC chairman is essentially the same as the conventional rap against him as presidential candidate a year ago. Namely, he reinforces all the party’s weaknesses. Democrats need to appeal to culturally traditional voters in the Midwest and border states who worry about the party’s commitment to national security. Dean, with his intense secularism, arrogant style, throngs of high-profile counterculture supporters and association with the peace movement, is the precise opposite of the image Democrats want to send out.

The conventional rap is completely right. But, in a way, Dean is even less suited to run the DNC than he is to run for president.

The DNC chairman has two main jobs. First, he transmits the party’s message — an important role when the party lacks a president and majority leaders in Congress. This job requires one to master the dismal art of “message discipline,” boiling down the party’s ideas into a few simple phrases and repeating them over and over until they have sunk into the public consciousness.

It’s a role for which Dean is particularly ill suited. During his campaign, remember, he fashioned himself a straight talker, delighting reporters by repeatedly wandering “off message.” On the plus side, he won friends in the media by appearing honest and human. On the negative side, he did himself enormous damage, when, for example, he suggested that he wouldn’t prejudge Osama bin Laden until he had been convicted in a court of law.

For presidential candidates, the negatives of “straight talk” usually outweigh the positives… In a job like party chairman, a loose cannon is nothing but downside.

The second major task of the DNC chairman is to run the party organization. And here, if this is at all possible, Dean looks even worse. Garance Franke-Ruta, who wrote sympathetic Dean pieces in the American Prospect during the campaign, spoke with several former Dean staffers. One called the candidate “a horrible manager” and added, “I wouldn’t trust him to run a company.” Another called his management style “just a disaster.”