When voters feel threatened they tend to vote conservative. Its not unusual for politicians to play on this fear and exploit the hate it generates. Its called the politics of hate. As to the Holocaust my own preference would be that the truth is told in order to prevent another one. I've said once or twice in another Israeli newspaper that there three versions of history - your version, their version and what actually happened.
Iran deal opposition grows among U.S. Republicans, Reuters poll shows (Reuters)
from the article: Netanyahu must stop hiding behind Holocaust warnings