When obama did become president, his spokesman, robert gibbs, asked you to be Obama's official photographer. Gibbs was as much an adviser as he was a spokesman for the Obamas. The amount of access that you get when you're the chief, official white ose photographer is totally dependent on relationship that you have with the president Ultimately, the president decides how much access you get.
Pete Souza has taken photographs for National Geographic, Life Magazine, and other dream outlets, leading to his ultimate subject as Chief Official White House Photographer, Barack Obama.