The recent poll taken here on FR is a prime example. The "still vote Republican" got 40% of the vote winning the overall poll but "vote third party" and "stay home" got over 60% combined. That is a big hit. Republicans can not win elections by alienating 2/3 of their base.
Meanwhile, the chastened Republican Party, which will have lost more than a few border moderates, will repackage itself and add a wall at the Southern Border as a core platform point. The Republican nominee in 2008 will probably support that point, and if he does the BorderBots will come roaring back to the polls and the Republicans roar back to the majority.
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False assumption --- that everyone participating in that poll is part of the "Base".