Traditionally, third party candidates perform best in races with no second party opposition. A Libertarian or Green running against an otherwise-unopposed candidate will do 10-20 pts better than one running against candidates from both parties.
If you go back to Bush v Gore, Nader underperformed his popular approval. It was Pat Buchanan who significantly over performed in Democrat districts. And that was largely attributed to the (deliberately) poor design of the Butterfly Ballot.
Traditionally, third party candidates perform best in races with no second party opposition. A Libertarian or Green running against an otherwise-unopposed candidate will do 10-20 pts better than one running against candidates from both parties.
If you go back to Bush v Gore, Nader underperformed his popular approval. It was Pat Buchanan who significantly over performed in Democrat districts. And that was largely attributed to the (deliberately) poor design of the Butterfly Ballot.