They were running conventional campaigns, and faded in the conventional manner. Trump is not, and has not.
How? Be precise...
Good God, where do you want to start: self-funding a partisan campaign, 100% name recognition, high profile business success, non-typical support trend lines, etc. Frankly, as I said earlier, questioning the unique nature of Trump's candidacy is the very definition of fatuousness.
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Is that your word of the day?