What you say is definitely true, and in our particular case we had a "common enemy" we were working to get away from so a lot of differences were set aside to focus on building an alternative.

I think the situation in the US is exacerbated by the fact that we have (effectively) a two-party political system. "Them... or us." In such a binary system there is little incentive for cooperation and reaching for resolutions... unlike multi-party systems where you have to negotiate and compromise in order to form a majority coalition. But "either-or" thinking runs throughout US culture... it was a thing I first noticed in sports when I arrived here... football, baseball, whatever games don't end in a draw; I came from soccer in the rest of the world where a draw is typically an acceptable outcome. We have been trained to REQUIRE a "winner" and a "loser."