[Dogbert41]

“How can the children and grandchildren of Jews, who suffered under socialism in both Germany and Russia, support the Democratic Party?”

Here is an interesting article that touches on that:

http://frontpagemag.com/2013/ronn-torossian/evangelicals-vital-for-american-support-for-israel/

[Praxeologue]

Your linked article does not provide an explanation, saying only that the contradiction is "odd":

Today, generations later, liberalism has now been amended to oddly reject Judaism. It seems that advocating for the rights of those who would see Jews and Israel disappear by opposing Jews as well has become the mantra of liberal Jews.