Comment by JKCalhoun

The U.S. has a Green Party, a Libertarian Party. If they ever had a chance to take any serious votes from the other two, one of the two major parties would co-opt enough of their platform to make the threat go away.

As we seem to be seeing, the Democratic Party in the U.S. is in fact, internally, two parties. As populations age out, we'll likely see the party itself evolve.