Bad taste, indeed. Russert needs to get some grief for that comment.
I think Imus instinctively knew Russert blundered, and so he did not comment.
Russert was discussing the supoena power involved when a party gains the majority in the House. He said republican majority started impeachment against Nixon, and Clinton. Russert said, "I'm not suggesting Democrats are planning to impeach Bush, in fact they have said they would not".
I want to remember that quote...branding my brain with a very specific Russert statement, I think, intentionally quoting a Democrat lie.