When America's ready for your policies, the major parties will steal them piecemeal.

That would be lovely, thanks.

In Germany if you do an across the board left-shift there's an analogous party structure:

  - Social Democrats (Democrats)
  - Christian Democrats (Republicans)
  - Liberals (Libertarians)
  - Greens

(There's also an additional Marixst party.)

Here the Greens and the Liberals (note that "liberal" outside of the US implies classical liberalism) grew up a lot as being a part of main-stream politics. I really wish that were possible in the US because it forces the other points in the political spectrum to actually deal with reality and softens their rhetoric in a pragmatic, but effective way. German Greens nearly as crack-potted as American ones as a result.