The Ku Klux Klan was a terrorist organization whose primary goal was to do what

help white Democrats return the power on the South

Explanation:

Ku Klux Klan started in the 19th century and was formed by the former Confederate army members. They were white supremacists who were against Northern leaders and black people, trying to take their rights of citizenship and political influence.

Their goal was to return power on the South to the white Democratic leaders. At the time, the platforms of two US parties were switched.

The first KKK did not manage to overthrow the Republican government in the South and was soon also disregarded by the Democratic party because of their criminal and violent activities.

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