Am I misinformed? As non American, I was under the impression that there could only be two parties, and everyone else had to be independent?
Usually, if you hear about a politician being an "independent," it means they're either a legislator not siding with either of the two major caucuses or a candidate running without the backing of any party, which does happen sometimes when a candidate is wealthy enough to fund themselves. The last time anyone managed get very far doing that nationally was Ross Perot in 1992, but when he ran again in 1996, he formed his own political party instead.
just a take, also non americam, dont' know why green and liberals don't stand a chanc to go to congress