U.S. President Barack Obama

As the 44th president of the United States, Barack Obama, 51, passed a revamp of the national healthcare system and authorized the raid that killed Osama bin Laden but struggled to revive the economy and create jobs.

Ahead of the U.S. presidential election on Tuesday, here are key facts about Obama, the nation's first black president.

- Barack Obama has a personal background like no other president in U.S. history. His mother, Ann Dunham, was a white woman from Kansas and his father, Barack Obama Sr., was a black Kenyan who saw little of his son after a divorce when the boy was a toddler. Obama spent much of his childhood in Indonesia and then Hawaii, where he lived with his maternal grandparents.

- Obama struggled with his mixed racial background while growing up, writing in a memoir that he wondered "if something was wrong with me." He also was troubled by the absence of his father, who he considered a "myth," and said that may have contributed to him using marijuana and cocaine in his youth.

- Obama graduated from New York's Columbia University in 1983 and then worked in the business sector in New York and for a Chicago community group. In 1988 he went to Harvard Law School, where he became the first black president of the prestigious Harvard Law Review.

- Obama's relationship with Congress is not great. Even when Democrats controlled the House of Representatives and the Senate, Republicans often stymied his initiatives. The situation became more difficult when tax-averse Republicans took over in the House in 2010.

- In the early 1990s Obama worked in a voter registration campaign in Chicago, taught constitutional law at the University of Chicago and joined a law firm that specialized in civil rights and neighbourhood development. He married Michelle Robinson, who he met at a law firm when he was an intern and she was assigned to be his adviser.

- In his rare spare moments, the lanky Obama pursues his lifelong love of basketball with semi-regular games at an FBI gym. He also makes time for school functions and sports events of daughters Sasha and Malia and tries to get out for an occasional "date night" with his wife.

- Obama's political career began with election to the Illinois State Senate in 1996 and soared in 2004 when he gave a rousing keynote address at the Democratic National Convention. In November of that year he was elected to the U.S. Senate.

- Obama won the 2008 Democratic presidential nomination by defeating Hilary Clinton, the former first lady and New York senator, and then took the presidency by beating Republican Senator John McCain. His energetic campaign was built on a theme of "hope and change" fuelled by powerful oratory.

- A mood of national optimism prevailed at Obama's January 20, 2009, inauguration, which drew an estimated 1.8 million people to the National Mall in Washington despite bitter cold. He began his presidency with a 68 percent approval rating.

- Obama simultaneously oversaw wars in Iraq, which he ended in 2011, and Afghanistan, as well as the U.S. military involvement in Libya that helped oust Muammar Gaddafi. In May 2011 he authorized the raid in which U.S. Navy SEALS killed al Qaeda leader Osama bin Laden in Pakistan - a triumph he points to as indicative of a strong national security policy.

- Obama inherited an economic crisis so persistent that it remains a threat to his re-election. Almost 800,000 jobs were lost the month he took over. In the early days of his administration, he pushed through an $831 billion economic stimulus package and renewed loans to automakers, even making the government a temporary part-owner of General Motors.

- The centrepiece of his domestic agenda was the Affordable Care Act, the healthcare reform law better known as Obamacare. Its purpose is to give all Americans affordable insurance and more protections but critics say it is expensive federal interference. A key aspect of the reform - requiring most Americans to get insurance or pay a penalty - survived a 2012 U.S. Supreme Court challenge.

- Obama has a reputation as a charming communicator but he also is criticized for being aloof and not building better relationships with congressional leaders. Some have questioned his preparation skills, especially after a sub-par performance in a presidential debate with Republican opponent Mitt Romney.