fact about constitution

The Philadelphia Convention adopted the U.S. Constitution on September 17, 1787 [01]. Anyone born after that date must be a natural born citizen in order to be eligible to serve as President of the United States [02].
President Obama's father, Barack Obama Senior (1936-1982), was a British East African (Kenyan) native who never became a U.S. citizen. President Obama -- regardless of where he was born -- acquired British nationality, at birth, by descent from his father. The President publicly admits that his citizenship status, at birth, was "governed" by the British Nationality Act of 1948 (see Barack Obama's "fight the smears" website).
FactCheck.org has confirmed President Obama's foreign citizenship at birth:

...at the time of his birth, Barack Obama Jr. was both a U.S. citizen (by virtue of being born in Hawaii) and a citizen of the United Kingdom and Colonies (or the UKC) by virtue of being born to a father who was a citizen of the UKC. (FactCheck.org: Obama's Kenyan Citizenship)

An increasing number of Americans are concerned that, since President Obama was born with foreign nationality (in addition to U.S. citizenship), he might not be a "natural born citizen" and therefore might not be eligible, under the Constitution, to serve as president [04].