Impeachment is a blunt axe that has been used twice in this country's history and in both cases in blatantly partisan fashion. Any Constitutional remedy that only works if the opposition party controls both house of Congress is no remedy at all. And resort to it in 2007 will only result in a huge backlash from a group of GOP partisans that are guaranteed to be plenty angry to start with.
If Democrats win control of Congress they need to concentrate first and foremost on removing the policy distortions that this administration has inserted into the economic and policy arenas, when it comes down to it Bush can't spend money he doesn't have.
We don't want Bush to go out with a Bang, we want him to go out with a Whimper. Impeachment would just bestow a Martyr tag on Bush for generations of Republicans to come, having him pack his bags in January 2009 with nothing but chaos to his credit is the fitting punishment.
What Bush fears more than anything else is for history to remember him as we do: "Worst President Ever". Let it Be So.
"The charges against President Johnson stemmed from the Tenure of Office Act of 1867. This law, which the Supreme Court declared unconstitutional in 1926, required the president to get the Senate's permission to remove any officeholder whose appointment it had to confirm.
Johnson was so angered by this challenge to the power of the president that he tested the law by suspending Secretary of War Edwin M. Stanton, the only Radical sympathizer in his cabinet, and replacing him with Ulysses S. Grant.
Eleven articles of impeachment were brought, charging Johnson with unlawfully removing Stanton and violating the Reconstruction Acts. The House of Representatives passed a resolution impeaching Johnson by a vote of 126 to 47."
http://www.pbs.org/newshour/impeachment/timeline/johnson.html
"For all practical purposes" Congress treated Johnson like a foreign occupier of the White House, even denying him the powers to appoint his own cabinet members.
As for the suggestion that the Democratic Party vanished in 1861 I would suggest that the organizers of the Jefferson/Jackson dinners would be profoundly surprised at knowing the Party mysteriously vanished.
Johnson was on the ticket as an attempt at ticket balancing, Republicans neither wanted nor expected him to become President. And the whole affair was partisan to the core.