"To run for president, each candidate must file two documents with the FEC: a Statement of Organization, which creates a federal campaign committee (such as Obama for America or John McCain 2008), and a Statement of Candidacy, which identifies the person running for office and the office being sought and officially links the candidate to the committee created in the Statement of Organization.
When you hear of people 'filing papers with the FEC' to run for president or some other federal office, these are the documents in question."
To announce or not: Explaining presidential exploratory committees
CNN.com:
