William Jefferson is a Democratic Congressman. There is also overwhelming evidence that he took a $100,000 bribe collected mostly by the FBI. He will be criminally prosecuted. He needs to resign now for the good of the party.
Colorado Democrats handled a far less serious incident involving Deanna Hanna that way in 2006, bringing the ethics charge against one of their own, rather than trying to cover it up. Admittedly, Colorado Democrats were secure in knowning that a vacancy committee of their own party would replace the incumbent. In the U.S. Congress, there are no such assurances. But, it isn't as if the Democrats in Congress hold a fragile minority either, as Colorado Democrats did in the State Senate. Do the right thing trumps any shortsighted idea of political advantage.
If Jefferson does not resign promptly, Democrats should get out front and initiate House ethics committee proceedings aimed at removing him from office, before the Republicans do. It takes a two-thirds majority of the House to remove a member. This is a case where that is appropriate, whether or not Jefferson is indicted or convicted. The sooner this happens, the sooner this matter is behind us. Decisive action in a clear case establishes a strong contrast between the Democratic approach to corruption and the Republican one.