If he's only going for caucus states, there are four still out there:
Kansas this Saturday, though that's Santorum country.
Hawaii next Tuesday. Long-shot, but worth a campaign stop.
Missouri has its spread out from the 15th to the 24th. A spread-out, confusing process is good for Paul (see Maine), and the fact that it already voted in February (adding to the confusion) can't hurt. Still very much a long shot.
Nebraska has its in early June---there's a good possibility that this is after the media claims the race is wrapped up, and it's another extended, confusing process.
That said, if your best shot at winning states is to bet on the obscure contests, isn't there only so much a PAC can do? Conventional advertising may draw more attention to the caucus itself (which is a bad thing for Paul) than get people to turn out for him.
