McCain & Graham want, above all else, to become the "recognized" face of the Republican Party, but Paul got in their way. Even if they disagreed with paul, they could have just kept quiet, but that would have meant the spotlight not shining on them.
Think about it this way: Despite a number of Democrats disagreeing with the Administration position, I didn't hear one of them attacking Obama in the same way McCain & Graham savaged Paul. Is there any wonder why the Dems are in power and the GOP is not? The Republicans might want to change their name to the New Whig Party, because they are becoming as irrelevant as the original Whigs and, if they don't tack back to their Conservative roots, they will become just as extinct