Many anti-imperialists worried that imperialism might threaten the American democratic system. Why would they think that?

Many anti-imperialists worried that imperialism might threaten the American democratic system because Imperialism is very strong and could have great impact on weaker countries as they have powerful government. Once imperialism came into power it can do anything as it wants and can extend its control over weaker countries.

Explanation:

Not all American citizens are imperialist. They were afraid of being captured by imperialist as imperialist had very strong power and they were aggressive also. Weaker countries were in fear of loss its identity to the powerful imperialist.

Imperialist had powerful government that can control or dictate the weaker countries. Imperialist believe in dictatorship or autocracy whereas America was in democracy. That democratic system would be violated by the action of imperialist it was the reason of worry to the non-imperialist.