Fast Rats
I am tempted to characterize the mass abandonment of GW by every element of his base with the traditional "rats off the sinking ship" metaphor, but I don't think I've ever seen rats move so fast:
http://www.realclearpolitics.com/articles/2006/05/the_base_vs_bush.html
http://www.nytimes.com/2006/05/15/washington/15dobson.html?ei=5089&en=f3bae0e611f1db9d&ex=1305345600&partner=rssyahoo&emc=rss&pagewanted=print
http://www.thehill.com/thehill/export/TheHill/News/Frontpage/050906/news1.html