Source:http://en.wikipedia.org/wiki/Barack_Obama_citizenship_conspiracy_theories

Conspiracy theories about the citizenship of Barack Obama claim that Barack Obama is not a natural-born citizen of the United States and is therefore not eligible to be President of the United States under Article Two of the U.S. Constitution. Some theories allege that Obama was born in Kenya, not Hawaii, or that his birth certificate is a forgery. Others allege that Obama became a citizen of Indonesia and lost his U.S. citizenship. Still others claim that because Obama's father was from Kenya, that means he held dual citizenship at birth (British and American), and the supposed dual citizenship means Obama is not a natural-born citizen of the United States. These theories have been characterized by some commentators as racist, or a racial reaction to the first African American president of the United States.
The claims have been promoted by a number of fringe theorists and political opponents, often referred to as "birthers", some of whom filed unsuccessful lawsuits seeking to disqualify Obama from running for, or being sworn in as President, or to obtain additional proof that he is constitutionally eligible to hold the office of President. Some Republican elected officials have expressed skepticism about Obama's citizenship or have displayed a lack of willingness to acknowledge it.[5] Republican members of the U.S. Congress and state legislatures have proposed and voted for legislation that would require presidential candidates to provide documentation of their qualifications to be president, including natural-born citizenship.
Belief in the conspiracy theories has persisted despite Obama's pre-election release of his official birth certificate from Hawaii in 2008,[1] additional confirmation by the Hawaii Department of Health based on the original documents, and the April 2011 release of a certified copy of Obama's original Certificate of Live Birth (so-called long-form birth certificate). Other evidence of Obama's Hawaii birth has surfaced such as birth announcements published in August 1961 in two Hawaii newspapers. Polls conducted in 2010 suggested that at least one quarter of adult Americans doubted Obama's U.S. birth, while a May 2011 Gallup poll found that doubts persisted among 13% of Americans and 23% of Republicans.