If you're opponent's standing in the bottom of a hole with a shovel in his hand, you stay out of view and let him dig.
We're also just coming into the campaign season. I'm sure that Howard Dean and the two campaign committes have been studying Gingrich's brilliant 1994 plan... and if they haven't they should all lose their jobs... and the Republicans didn't start the "Contract with America" campaign until late September. Clinton was in trouble with the voters, (the worst of his presidency, as it turned out,) the Democrats were an intrenched powerful majority presiding over a scandal-plauged Congress, and the Republicans let them stew for a long time. They waited until the end to really campaign hard. They grabbed all the headlines, put the Dems on the defensive, and gave them no time to respond. It worked perfectly.
As to impeachment, the Dems haven't backed off of it, because they were never on it, at least not publicly. The only people who were saying that the Democrats would impeach the President have been Republican political consultants. It's a transparent attempt to motivate that portion of the base that truly believes in Bush. Whether or not the Dems will impeach Bush if they get the majority, I don't know. I suspect many of them would like to. But they haven't been saying so.
To ascribe sinister motives to backing away from a position you haven't taken seems a bit premature, at least to me.
--Shannon