Even if by some freak accident the democrats took over the House and impeached the President, it is highly unlikely that they could garner 2/3 of the entire Senate to convict him.
If Democrats can't stick together to defeat a fairly unpopular bankruptcy bill, or a trade agreement that not that many people outside of the beltway feel much love for, I doubt they could find the votes to impeach in the House, even if they had majority after November.
I am convinced there must be some money dems, political consulting dems, and plain old moderate dems that must be pulling their hair out right now over this looney left. Can you imagine if the Dems got controlled and Conyers is head of the JUdicary committee with subpoena power. These folks think their on a "mission from God" as to impeaching Bush and trying to put him in jail for goodness sakes too. Its like viva revolution and damn the consequences for the Country. I was not too thrilled about Impeachment against Clinton I will admit. BUt if this happens even if just articles are submitted a horrible precedent is unleashed. Some grownups in the Democractic party better take control quick. I mean we would get short term political gains from this lunacy , but I would hate to see the result of our institutions at the end. And this happening while we are at war. Unbelievable.
I suspect that if they tried that it would be a huge backlash and the republicans would regain the house in 2008 as well as retain the White House. People want them to work on their behalf, not do impeachment nonsense.