The worst-kept secret in Washington is about to be revealed: President Obama is expected to nominate former Enron prosecutor Leslie R. Caldwell to head the Justice Department’s criminal division. We hear the move is likely to be announced this week.

Caldwell, who led the Enron Task force — and hired now-White House Counsel Kathy Ruemmler to work on it — is in private practice in New York.  Pre-Enron, she was chief of the criminal division and the securities fraud section in the’s office for the northern district of California and before that was an assistant U.S. attorney in the Eastern District of New York,