Unless Huckabee starts raising some serious money or his grassroots support shows significant ability to self-organize beyond Ames, he’ll have trouble staying in the race as long as Paul. But you are right that Paul’s foreign policy views, while a significant driver of his support, do put a ceiling on the number of regular Republicans he can pick up in a primary.
Which answers your earlier question about which candidates Paul would take votes from: Probably not very many from any of them, since a Republican or independent drawn toward Paul is probably too alienated from the rest of the Bush-era GOP to find the others an acceptable second choice (though he might pull a few votes from lower-tier candidates like Tom Tancredo). Paul’s bid will mostly just keep these people voting in the Republican primaries.
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