Perot thought the same thing.
A lot of those disaffected Democrats like Bernie Sanders more than Donald Trump, and the Democrats who do like Trump are ones who might otherwise have voted Republican.
One major party or the other can muster at least 33% of the vote in pretty much all the states and that's enough to win in a three-way race.
Third party Trump might come in second in some states (as Perot did in Maine and Utah), and for a third party candidate that's very good, but I don't see him winning the election.
I think Trump could actually win third party.
Perot thought the same thing.
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Ross Perot is no Donald Trump. Besides, it was a different time and a different landscape of the nation in 1992. A lot has changed in the last 24 years.