The Presidency of Barack Obama began on January 20, 2009, when Barack Obama was inaugurated as the 44th President of the United States, and ended on January 20, 2017. Obama, a Democrat, took office following a decisive victory over Republican John McCain in the 2008 presidential election. During his tenure, Obama oversaw the implementation of the Affordable Care Act, the Dodd-Frank Wall Street Reform and Consumer Protection Act, the Don't Ask Don't Tell Repeal Act of 2010, and the American Recovery and Reinvestment Act of 2009. He also ordered U.S. military involvement in Libya in 2011, leading to the overthrow of Muammar Gaddafi. Obama also presided over the implementation of the Paris Agreement on climate change in 2016.