What were the worst ethics charges? If it were merely that he taught a college class and misclassified it as tax-exempt, it's doubtful that fellow Republicans would care that much. He had to have really done something, perhaps even behind the scenes, to piss them off.
That sounds more like it. There was probably much more to it, too.
He was a bit of a tyrant to his party, plus his blatant moral hypocrisies--probably something that the true believers in the Republican party could never be comfortable with.
the violations were long before his recent consulting shenanigans. I'll try to find some more details; but don't discount "misclassifying courses as tax-exempt" as something benign when it comes to ethics. It all depends on your position at the time, and ethical conflicts related with ones various responsibilities. Even a handful of supposedly "mild" violations bespeaks volumes towards the character of someone that chooses to serve the public.
Here's an archived summary:
http://www.washingtonpost.com/wp-srv/politics/govt/leadership/ethics.htm
seems that his
84 violations were eventually dropped for "lack of evidence." haha
In this article:
http://www.washingtonpost.com/wp-srv/politics/govt/leadership/stories/012297.htm
It mentions that such a charge and reprimand had never been levied against a Speaker in the 208 year history of Congress. Whether or not they were eventually dropped, such charges do not come lightly, nor without reason.
It is not shocking that anyone who has ever worked with this guy refuses to support him, and fundamentally believes that he would be a disaster for this country.