Why don't you think that? Is there anything in Article II, Amendments XII or XXII, or anywhere else in the Constitution, that supports this view?
You think a person who is the citizen of a foreign nation can be the leader of the United States?
Not even constitutionally, but for security clearance.
Read the DOD’s website regarding security clearance with dual citizenships and/or passports.
http://www.dod.mil/dodgc/doha/isp.html