Natural born status of presidential candidates has been an issue since 2008. For example, co-sponsors Hillary Clinton and Barack Obama supported a resolution declaring that "John Sidney McCain, III, is a natural born citizen" since people questioned McCain's status as he was born in the Panama Canal while his American parents were in the U.S. military.
The Obama long form birth certificate does not state that both of his parents were American citizens.
One crucial issue is natural born citizenship:
Article 2 Section 1 Clause 5 of the United States Constitution states:
No person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President."
On the other hand, any ordinary or naturalized citizen can be a Senator as defined in Article 1 Section 3 as follows:
No Person shall be a Senator who shall not have attained to the Age of thirty Years, and been nine Years a Citizen of the United States.
Other questions unanswered are: did Obama become an Indonesian citizen when his mother re-married and the family lived in Indonesia?
Was Obama actually Barry Soetoro and did he attend U.S. colleges as Soetoro?
His nanny was an openly gay man who, in keeping with Indonesia’s relaxed attitudes toward homosexuality, carried on an affair with a local butcher, longtime residents said. The nanny later joined a group of transvestites called Fantastic Dolls, who, like the many transvestites who remain fixtures of Jakarta’s streetscape, entertained people by dancing and playing volleyball.
In any event, people knew Obama as Barry.
To clarify other periods in his life more documentation is needed.
For example, there are still no documents for Obama's career, including his passport records, kindergarten records, Punahou school records, Occidental College records, Columbia University records, Columbia thesis, Harvard Law School records, Harvard Law Review articles, University of Chicago articles, Illinois State Bar Association records, Illinois State Senate records and schedules, medical records, Obama/Dunham marriage license, Obama/Dunham divorce documents, social security number, Selective Service records, Soetoro/Dunham marriage license and adoption records.
As for the long form birth certificate itself, others from the time differ from the one released by the White House.
Susan Nordyke’s certificate, born one day after Obama, clearly reveals differences (click image for larger picture):
On April 22 Obama requested the release of the long form birth certificate.
Obama releases birth certificate
Obama's Remarks on Long Form Birth Certificate Released By White House: 'Carnival Barkers'
The key is to define the status of a natural born citizen.