Freud had a felicitous phrase for the psycho-dynamics of this sort of thing. He called it "the narcissism of small differences."
I am happy to report that this affliction of self-destruction seems now to have been visited upon the right in America. The latest evidence is the vitriolic reaction of folks at the American Enterprise Institute to the departure of David Frum. Frum says he was fired as a result of donor pressure. Charles Murray, who describes himself as a long-time close friend of Frum and his wife, calls this a despicable calumny and says that this judgment will no doubt lead to the end of the friendship. [For those who are totally clueless, hit the internet and find Frum's very recent opinion piece calling the Republican hostility to health care reform a strategic Waterloo.]
Perhaps I should not go on. As Napoleon is reputed to have said to one of his Marshals during a battle, "When your enemy is making a mistake, do not interrupt him."