Joe Biden served as the 47th vice president of the United States during the presidency of Barack Obama from January 20, 2009, to January 20, 2017. Biden, a member of the Democratic Party who previously served as a senior U.S. senator representing Delaware from 1973 to 2009, was selected as Obama's running mate and took office following their victory in the 2008 presidential election over Republican nominees John McCain and Sarah Palin. Four years later, in the 2012 presidential election, they defeated Republican nominees Mitt Romney and Paul Ryan, to win re-election. Biden was the first vice president from Delaware and the first Roman Catholic vice president in U.S. history.
Alongside Biden's vice presidency, the Democratic Party also held their majorities in the House of Representatives and the Senate during the 111th U.S. Congress following the 2008 elections, attained an overall federal government trifecta. Biden was more influential than most vice presidents due to his long Senate career and relationships with both members of Congress and politicians abroad. His relationship with Republican Senate leader Mitch McConnell was particularly important after the Republicans regained control of Congress in the 2010 and 2014 elections, and the two were instrumental in ending the 2011 and 2013 debt-ceiling crises.