For one thing, Jews have never been very popular among European nations.
The Jew was the eternal "outsider", he, or his parents, or grandparents, always came from some where else.
There is a joke about real Yankee's, when asked "is So and So a native?" the reply is "No, his folks came from away."
That was the Jew, in a world of "us", and "them", he was always a "them", never an "us".
In medieval times laws were passed to prevent them from owning land, or engaging in many trades, so many were forced to become traveling peddlers, then traders, and merchants, at a time when cash money could be scarce even for Kings the Church forbade "usury", which at the time was considered any lending of money for profit.
The Jew faced no such restrictions and many a fancy King was in hock up to his crenelations to Hymie the pack peddler.
When a disaster comes, war famine, plague, the blame first goes to 2 groups, "them", and "the wealthy", the Jew was seen as both through out history.
The second reason that Jews were so unpopular was the association between Jews and Communism.
In our own history the connection between the influx of East European Jews and the rise of labor unions and socialism is easily documented, Europe was even more so earlier, and to a greater extent.
The most glaring examples come from the Russian Revolution ,
Vladimir Lenin,
http://en.wikipedia.org/wiki/Vladimir_Lenin born Vladimir Ilyich Ulyanov,
and Leon Trotsky
http://en.wikipedia.org/wiki/Leon_Trotsky born Lev Davidovich Bronshtein
Both were Jews first introduced to leftist politics through Jewish socialist and Zionist politics.
How many Jews now in America vote Democrat ?
So if you have a wealthy , socialist, outsider, it is a recipe for "Scape goat" that, (minus the socialist tag ) is still be used by Obama.
That's how it happened.
Saul Alinsky, ( another liberal Jew ) hit on an interesting fact in "Rules for radicals", it is a scientific formula, like chemistry or Gravity that can be codified and duplicated as was done by Slobadan Milosivic in the former Yugoslavia.