It is an article of faith among professional politicians that a divisive primary battle can be fatal to a successful general election campaign. Richard Nixon once told a bewildered group of visitors to his Saddle River Elba that Rep. John Ashbrook's primary challenge had been a major distraction of the 1972 re-election campaign. Most of those gathered had no memory of Ashbrook or the Ashbrook campaign (it began and ended with the New Hampshire primary) and couldn't imagine that it had caused the former president a moment's worry. But Nixon was adamant on the point. Divisive primaries were, he said, in all cases and without exception, "bad news."
Incumbents can, if they're skillful, avoid primary challenges, but what if yours is the out party? The presidential primaries and caucuses produce your nominee; the road back to the White House begins with 7-10 hyper-ambitious people killing each other off to become The One. So what does a political party do to minimize the damage of that fight?
http://www.techcentralstation.com/091903A.html