It will be faction. The authors of The Federalist Papers saw faction as a leading threat.
You made an excellent observation, one which people should pay more attention to.
"Faction" is an important term that is defined as: "a party or group (as within a government) that is often contentious or self-seeking".
Not only can it be applied to our political leaders, it can also apply to illegal immigrants. America is in danger from both groups.
However, I believe the main reason for concern is because we have lost our way as a God-fearing nation and ignored warnings given by the Jonahs in our midst.