The Constitution of the United States provides several basic requirements for eligibility to be elected to the office of President. Individual states did not introduce significant relevant legislation until the 2008 election of Barack Obama, when a controversy known as the birther movement was promoted by various conspiracy theorists. The "birthers" asserted during the 2008 presidential election campaign that Obama was not a natural-born U.S. citizen, as mandated by the Constitution, and thus was ineligible to be President of the United States, prompting several state legislatures to consider legislation aimed at requiring future presidential candidates to provide proof of citizenship by birth before being granted ballot access in their state. None of these efforts led to the passage of currently active laws.