Jack McCain, son of Sen. John McCain, R-Ariz., touches his father's casket during a memorial service at the Arizona Capitol on Wednesday in Phoenix. Ross D. Franklin/AP hide caption
Barack Obama
Former President Barack Obama speaks in Johannesburg on Tuesday at the centennial of Nelson Mandela's birth. Gianluigi Guercia/AFP/Getty Images hide caption
'We've Been Through Darker Times': Barack Obama Speaks In South Africa
Merrick Garland was nominated to the Supreme Court by President Barack Obama in March 2016. The Senate never voted on his nomination. Chip Somodevilla/Getty Images hide caption
Then-President Barack Obama helps paint a mural of Martin Luther King Jr. in 2017. Susan Walsh/AP hide caption
Obama stands between the portraits. His will be permanently installed in the "America's Presidents" exhibit at the National Portrait Gallery in Washington, D.C. Mark Wilson/Getty Images hide caption
Democratic gubernatorial candidate Andy McGuire pitches herself to caucus-goers in the Roosevelt High School Auditorium in Des Moines during the Iowa Caucuses on Feb. 5, 2018. Clay Masters/Iowa Public Radio hide caption
Prince Harry interviewed former President Barack Obama in a broadcast that aired Wednesday on the BBC. The interview was recorded during September's Invictus Games in Toronto, where the two are pictured here. Chris Jackson/Getty Images for the Invictus Games Foundation hide caption
Researcher Elizabeth Currid-Halkett says celebrity can be boiled down to a simple formula. Caiaimage/Sam Edwards/Getty Images/Caiaimage hide caption
Joe Biden and his son, the late Beau Biden, embrace at the 2008 Democratic National Convention in Denver. Beau Biden delivered the keynote address that year. He died seven years later from brain cancer. Spencer Platt/Getty Images hide caption
Former President Barack Obama extends his hand as he attends Cook County jury duty at the Daley Center on Wednesday in Chicago. Joshua Lott/Getty Images hide caption
Former President Obama speaks during a campaign rally for Democratic gubernatorial nominee Ralph Northam in Richmond, Va. Jim Watson/AFP/Getty Images hide caption
Then-President Barack Obama in a 2015 meeting with a group of DREAMers, who received protection from Deferred Action for Childhood Arrivals. Obama reacted strongly to President Trump's reversal of the policy. Win McNamee/Getty Images hide caption
Former President Barack Obama's tweet after the violence Charlottesville, Va., is now the most-liked tweet ever. The tweet quoted Nelson Mandela and included this photo of Obama visiting a daycare in Maryland. Pete Souza/The White House hide caption