John Fonte of the Hudson Institute is very serious about the issue of dual citizenship.
if our great historical success in assimilating millions of immigrants is going to continue, ultimately newcomers must be loyal to the U.S. Constitution and not to any other constitution.

“we are betting” Mexican-Americans will “think Mexico first”

If the United States accepts the principle that it is legitimate for foreign-born citizens (or, worse, for their American-born children) to maintain political allegiance to the foreign state from which they emigrated, we have accepted a racial-ethnic definition of citizenship that makes a mockery of our 200-year old immigration ideal.
In effect, Americans would have accepted the old Germanic concept of das Volk (or Latinized, its Spanish equivalent of La Raza) in which the “race” trumps citizenship.

It means dual citizens are, in effect, privileged “supra-citizens” because unlike other Americans they have voting power in more than one state and are loyal to more than one constitution. sanctions would serve two purposes: (1) to discourage the practice, and (2) to remind everyone (Americans and the rest of the world alike) we are serious about the Oath of Allegiance and about our traditional ideal of political rather than racial or ethnic citizenship.

Singer has argued that it was important for the U.S. to remove Saddam because “some of the scholars with the deepest understanding of Muslim history and culture, is to compel the Arab governments to act against terrorism and stay away from WMD by making them afraid of what will happen to them if they fail to do so.”