To tell you the truth, I feel it is an ineptitude that was brought over from the old country. Many Jews embraced Socialsim, Liberalism, Communism, Marxism etc. after the 1880's pogroms. During Enlightenment/Emancipation in Europe...many Jews embraced the Utopian "thinking" classes and threw off their Conservatism/Jewishness to "melt". The ilk you see now are the remnants of these misgided Judenrot that wouldn't know logic, nor morality if it slapped them in the face. You hit it when you said that they show support for Carter. I'd add shvartzas like Jackson and Sharpton to that. The funny thing is "thinking" Jews like Dershowitz came out against Carter's book and Carter himself but I still don't think his mind has grasped the inherent debasement of the Leftist ideology/mind.
Good question... One can add to that...if America is anything like Canada... People vote Democrate because "their parents did"...but they are ignorant to the entire agenda, platform, illogic/ineptitude of leftist thought...
"Ignorance and arrogance are the poisons of the Liberal mind" - Rav Meir Kahane...