Anything can happen, but it’s extremely unlikely that a Nazi-type party would ever take power in the US.
However, a holocaust could still occur. All it takes is one nuclear bomb or missile from North Korean or Iran or ISIS, to kill millions of Jews in NYC. The US has a strong military but sometimes defenses fail and snafus happen.
If a nuclear missile was being shot at NYC or Israel, or a bomb was being sneaked into a NYC harbor, then perhaps the US and Israeli militaries would have a roughly equal chance of stopping it before it explodes.
However, Israel might have a slight edge in this regard, since they have had more experience with wars and missles on their turf and are more effective at thwarting real terrorist attacks.