If you are presumed to be a U.S. citizen at your birth, and no government entity says otherwise, then in fact you are.
Seems rather contradictory to Obama's web site which states:
"As a Kenyan native, Barack Obama Sr. was a British subject whose citizenship status was governed by The British Nationality Act of 1948. That same act governed the status of Obama Sr.‘s children."
Could another nation declare an American citizen one of their citizens and thereby make him/her ineligible for the presidency? For example, in the last election if Panama passed a law declaring McCain a citizen of Panama would he then not be eligible to become president if he won?
If that’s the case, then any foreign power could disqualify any US presidential candidate. Just wondering.