Nancy Pelosi has managed to severely scar her leadership even before taking up the gavel as the new speaker of the House. First, she played politics with the leadership of the House Intelligence Committee to settle an old score and a new debt. And then she put herself in a lose-lose position by trying to force a badly tarnished ally, Representative John Murtha, on the incoming Democratic Congress as majority leader. The party caucus put a decisive end to that gambit yesterday, giving the No. 2 job to Steny Hoyer, a longtime Pelosi rival.

But Ms. Pelosi’s damage to herself was already done. The well-known shortcomings of Mr. Murtha were broadcast for all to see — from his quid-pro-quo addiction to moneyed lobbyists to the grainy government tape of his involvement in the Abscam scandal a generation ago. The resurrected tape — feasted upon by Pelosi enemies — shows how Mr. Murtha narrowly survived as an unindicted co-conspirator, admittedly tempted but finally rebuffing a bribe offer: “I’m not interested — at this point.”

Mr. Murtha would have been a farcical presence in a leadership promising the cleanest Congress in history. Ms. Pelosi should have been first to realize this, having made such a fiery campaign sword of her vows to end Capitol corruption. Instead, she acted like some old-time precinct boss and lost the first test before her peers.

The argument most often cited for bypassing Harman is that under House rules, her rotating membership on the Intelligence Committee is about to expire. But Harman's supporters note that since 2003, term limits on the committee (which in any case can be waived) don't apply to the chairman and ranking member. They also point out that the independent 9/11 commission called in its recommendations for longer tenures on congressional intelligence panels as a way of fostering continuity and institutional memory.

Then there is the claim that awarding the chairmanship to Harman rather than Hastings would offend the sacred principle of seniority, as well as the sensibilities of the Congressional Black Caucus (Hastings is African American).

Seniority has never been the only criterion for the awarding of committee chairmanships in either party. As for black representation in the leadership, two other African Americans, Reps. Charles B. Rangel (D-N.Y.) and John Conyers Jr. (D-Mich.) are slated to head the Ways and Means and Judiciary committees, respectively.

The most substantial — and alarming — speculation regarding the Harman-Pelosi rift is that the speaker may consider Harman too moderate. If one of the reasons Pelosi backed Murtha was because he took it to Republicans on the war in Iraq, Harman — who initially supported the war — may be insufficiently partisan in Pelosi's eyes.

Pelosi, who has vowed to lead the House from the center, should think twice before indulging in a witch hunt of colleagues who can work well with Republicans.