First of all, I’d like to know how YOU know it was a US passport and secondly, you can get US passport’s WITHOUT a BC.
No, I have not personally viewed Obama’s passport.
Passport requirements - proof of US citizenship
You can prove your US citizenship with one of the following:
Original Birth Certificate (if born in the United States);
or Old (undamaged) passport;
or Original Certificate of Citizenship or FS-240, DS-1350 ( if born outside the US );
or Original Certificate of Naturalization issued by the Immigration and Naturalization Office.
If Obama used an FS-240 or ds-1350 form indicating that he was born outside the US or if he has been naturalized by the INS, those records would be on file at the US State Department.