Barack Obama, a Democrat and America's first black president, was re-elected for a second term in November 2012 after a bitterly-fought campaign against Republican challenger Mitt Romney.
The Democrats kept control of the Senate and the Republicans remained in control of the House of Representatives, leading to political gridlock in Congress on the budget in late 2013.
The campaign focused on the ailing US economy. In his inaugural speech in January 2013, Mr Obama called on Democrats and Republicans to work together to sustain the country's fragile economic recovery. He also pledged an end to "ten years of war", signalling the departure of US troops from Afghanistan in 2014.
First term challenges
The worst economic crisis in the US since the Great Depression of the 1930s dominated much of Mr Obama's first term. The president pursued an aggressive policy of economic stimulus, including bail-outs of major car makers.
He made reform of the healthcare system to extend coverage and reduce ballooning costs one of his top domestic priorities.
Despite a tortuous drafting process and vociferous Republican opposition, Mr Obama and Democrats in Congress finally succeeded in passing a health care bill in March 2010.
However, the health reform, along with the $787bn stimulus package passed in February 2010 to shore up an ailing economy, galvanised opposition among opponents to Mr Obama's agenda.
The American Right in particular worried about what it saw as moves to extend the role of the state in the economy, and the threat of excessive public debt.
Tea Party boost for Republicans
The rise of the conservative Tea Party movement in 2009 re-energised the Republicans and helped them to capitalise on popular discontent at the slow pace of America's economic recovery.
The Republicans made sweeping gains in mid-term elections in November 2010, regaining control of the House of Representatives.
In autumn 2011 anti-capitalist protestors took to the streets of major cities, marching under the slogan "Occupy Wall Street", against "corporate greed" and increasing government debt. The protests inspired marches in other cities worldwide in October 2011.
Bin Laden operation
In May 2011, Mr Obama was widely applauded domestically - including by the Right - for his decision to order the operation that killed Al-Qaeda leader Osama Bin Laden.
Barack Obama was born in 1961 in Hawaii, the son of a black Kenyan father and a white American mother. After attending an elite Hawaiian academy and Columbia University in New York, he went on to Harvard Law School, where he graduated in 1991.
Mr Obama practiced law and did community work in Chicago, where he also became active in the Democratic Party. He won a seat in the Illinois state senate in 1996, and followed this up by winning a US Senate seat in 2004.
He emphatic victory over his opponent John McCain in the 2008 presidential election ended eight years of Republican rule in the White House.
Mr Obama ran for president on a ticket promising change, and came to office riding a wave of high expectations from his supporters, both at home and abroad.
He is widely acknowledged to be a charismatic figure and is noted for his stirring oratory.