Your citizenship could be revoked if, within 5 years of naturalization, the U.S. government proved you joined a subversive group. Such groups include Al Qaeda and the Nazi Party, for example.
Your citizenship could be revoked if, within 10 years of naturalization, you refused to testify before a U.S. congressional committee investigating your involvement in an allegedly subversive act. Subversive acts include trying to harm U.S. officials or overthrow the government.
If you lied or concealed relevant facts in order to obtain U.S. citizenship, your citizenship could be revoked. This is called illegally procuring citizenship.
Arthur Herman: Romney's Trump impeachment vote - why Republicans should thank the Senator
... But Trump’s successful handling of U.S. domestic, as well as foreign policy, has been in defiance of that elite. It has shattered forever their claims that without their constant guidance the result could only be chaos. Even more important, Trump has also proved that when the elite are challenged they will band together to remove a president by any means fair or foul who has proved them to be impotent and wrong.
By his vote, and the media furor swirling around it, Romney has made this clash between Trump and our self-ordained elite more evident than ever. We can see that Romney’s strategy for his political future is, ironically, to join up with the very same people and media who wrecked his reputation and presidential campaign in 2012 It demonstrates that whether they are Democrats or Republicans, liberals or conservatives, their claims to being an American aristocracy without whom the country cannot survive binds them together closer than any other loyalty - even a loyalty to the truth....
Based on what we know now, the list of subversive groups should be expanded to include the Democrat Party.