Sorry, but I'm ignorant as to the Deardorff reference.
One thing I've noticed about the Third Party thing is that they try to start at the top. The result is that they work their way down. Ross Perot is a classic example; where is his party-effort, today?
The Republicans used to do this in Texas. There would be some well-to-do fella who'd have a heckuva radio campaign, but he was rarely previously ever heard of. No grassroots effort on the part of the party. This changed during the 1970s, and now the state is Republican controlled.
Right now, the Greens seem to be achieving the most gains. They've earned a permanent spot on some ballots in some voting jurisdictions. And it's all through grassroots hard work.
Could be that Libertarians are much like gunowners and ranchers. Just too independent, and too busy trying to make a living, to gather up in large wads to organize and create voting strength.
The election laws militate against third party efforts in many states, but not all. I don't know about "cahoots", but there is a pretty good argument about third and fourth parties.
Italy is one of the worst-case examples. I think they have some 30 different political parties there. The problem, really, is simple: With multiple parties, it takes a coalition to get elected. Coalitions can win elections, but they cannot govern. The competing interests soon diverge, and you wind up with total gridlock. Of course, some say that's a Good Thing, and I don't know as I disagree.
In this country, the Democratic party is made up of coalitions, mostly victim groups. You see the results; they can only agree that they hate Republicans and other than that, raise taxes for more social programs...
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