But what if he doesn't? Politicians are known for stubbornness, and Jefferson has not shown himself to be the cooperative sort on this issue in the past. Mark Kleiman has the answer:
T]here is Constitutional authority to expel a member, by a two-thirds vote. Jefferson, along with several of the not-yet-indicted Abramoff/MZM crooks, ought to be called before the Ethics Committee and asked under oath where the money came from. He would have the right to plead his Fifth Amendment privilege against self-incrimination, on which the Committee would have the right to draw the appropriate inference and recommend his expulsion.
No, this isn't a violation of the principle “innocent until proven guilty.” The question isn't criminal guilt, it’s fitness to serve in the House. Whether Jefferson, Doolittle, et al. go to prison is up to the prosecutors and the courts. Whether they continue to make our laws is up to the House of Representatives.
Jefferson is quite corrupt, and certainly deserving of expulsion. But he's not the only one--there are serious allegations surrounding Reps. John Doolittle and Jerry Lewis (R-CA) as well, and I know there are others. But let's just take Doolittle, as he's probably the most serious case. Put them both in front of the committee, make them both testify, and if they aren't able to provide some good answers, vote to expel.
Democrats, of course, don't have the two-third majority by themselves to get Jefferson and Doolittle out. But therein lies the beauty. If Republicans vote to expel both, great--we've gotten rid of two corrupt Congressmen. No loss. But if Republicans vote to expel Jefferson, but not Doolittle, it will look like they're covering their own, thus solidifying the "culture of corruption" meme as a GOP problem while the Democrats show themselves as firm and intolerant of corruption, even in their own ranks. And if they vote to expel neither, they'll just look ridiculous.