The Libertarian and Constitution Parties are both isolationist. However, many libertarians (Neal Boortz, Larry Elder) are not isolationists.
Those two are somewhat an exception.
The Paul, Baldwin, etc bunch with their isolationist , 9/11 truther, legalize marajuana, etc. views only receive
as much as 3% of the votes, just enough to throw elections to the Liberal candidates and they have over the years.